A dim-witted pervert from the local Kuou Academy, the unlucky Issei is brutally killed on his first date by his current girlfriend, who happens to be a fallen angel. He is resurrected by the beautiful Rias Gremory as her Pawn. He then learns awakens to his Sacred Gear Boosted Gear.
Known by most at his academy for being a extreme pervert and mostly dim-witted, the unabashed Issei Hyoudou takes life one day at a time, no matter what problem that it may throw at him. He recently became the boyfriend of the beautiful and friendly Amano Yuuma, but is soon killed by her when she reveals her true form and purpose to him. He is resurrected by the powerful Rias Gremory, a high-level devil who is tasked with dealing with and fighting the fallen angels who seek to destroy the powerful divine weapons. He becomes Rias's Pawn and learns he will be her only pawn due to all eight Pawn pieces being used on him though half of them are mutation pieces which are made to contain a larger amount of power. That power is the power of the Red Dragon Emperor Ddraig who was sealed in the form of a Sacred Gear known as the Boosted Gear.
Issei Hyoudou was created by Ishibumi Ichiei for their work on the Highschool DxD franchise. As of now, it is not known as to what inspired them to create this character.
We are first introduced to Issei Hyoudou in the Highschool DxD story when he is shown walking with his new girlfriend Amano Yuuma at the local park. Being his first ever date, Issei was surprised when Amano decided to take him out to the park with her. Unfortunately for the hapless Issei, Amano is not the loving girl that she appears to be, and when they arrive at a isolated section of the park, she unleashes her hidden powers against him. Wings of pure blackness emerge from her back, and before the dumbfounded Issei has a chance to comprehend what the hell is going on, she takes aim and hurls a large spear of light that rips through his chest, mortally wounding him. As he falls to his knees from his devastating wound, she reveals to him the truth about her true intentions, telling him that she had fun with him, but since he was a potential risk to her mission, she had no choice but to eliminate him. He is also told by her that his demise has to do with a scared relic that was hidden inside of his body, and with her former friend mere moments from dying, she takes her leave, leaving him to bleed to death in the middle of the park. As he succumbs to the cold and dark blackness of death, a mysterious female approaches the area where the attack took place, taking interest in the plight of the slain boy who lies dead in the middle of the grove. Using her demonic powers, she brings him back to life, making him her newest servant in her ongoing struggle against the fallen angels, like the one who had killed him minutes earlier.
The loud cries of his tsundere-themed alarm clock shakes the weary Issei from his fitful slumber, wondering as to why he has had such a vivid and terrible dream about being killed by his girlfriend Amano. As he makes his way outdoors and towards the prestigious Kuou Private Academy, Issei takes notice of how the bright sunlight seems to cause a sharp pain for him, as if the very light radiating from the sun was slowly sapping his energy away. Thinking back, he wonders about how he seems to have such wild and vigorous levels of energy after the sun sets and for the duration of the night, but how the opposite happens whenever the sun is out. Irritated by the sunlight and the fact that it is the beginning of another long day at the academy, Issei reaches the front gates and heads towards his homeroom for his classes. He barely has time to sit down at his desk before he begins daydreaming about having his own personal harem filled with beautiful women, the mere thought of being surrounded by naked women bringing a smile to his face as he is then interrupted by his friend and fellow pervert Matsuda, who asks him about the porn dvd that he loaned him the other day. Enraged that his friend would ask him that kind of question in front of the female students aloud, Issei begins tussling with Matsuda, telling him not to speak of such things aloud as they are approached by another student, who watches their struggle with mild amusement. Realizing that it is only Motohama, another perverted student in his class, Issei stops his struggling with the roughed-up Matsuda and turns his attention to Motohama, who goes on to praise the "divine" winds that revealed the panties of multiple female students to him earlier that morning. Recovering from his scuffle, the grinning Matsuda digs through his bag and pulls out his newest prized possession, a rare first edition copy of an eroge movie that was out of print and is considered to be one of the best ever created. When the harsh comments from the disapproving female students reach his ears, Matsuda goes into a rage, knocking desks over as Issei ends up having to restrain his rampaging friend, with no help from the engrossed Motohama who stares at the movie box with glee.
After Matsuda calms down, Issei brings up his experiences with his girfriend Amano Yuuma in their conversation, and is somewhat shocked to notice that they both have absolutely no idea what he is talking about. While his friends poke fun at the idea of him ever having a girlfriend, Issei has a flashback to the previous week, when he introduced the smiling Amano to his flabbergasted friends, who were in shock that someone as perverted as Issei could win the affection of a real girl so easily. Like everyone else at the academy, no one seems to remember Amano ever existing, and this troubles Issei because he knows with his heart that he met her, spent a week with her, and became her boyfriend much to the envy of his friends. In his mind, it seems that everyone has forgotten that she had ever existed, and it appears that it has been that way since he had that "dream" in which she brutally killed him in the park on their date, leaving him there to die as she flew away. Disappointed, Issei frowns and tries to clear his head, but a minor disturbance being caused by the female students in the hallway outside of the classroom not only catches his attention, but the attention of his friends. Making their way into the hallway, they get close to the windows and look down onto the campus grounds, finding the thing that has all of the female students in such a tizzy at the moment. Walking towards the front entrance of the academy is the beautiful Rias Gremory, a 3rd year student at Kuou Academy and the most beautiful females ever to attend classes at their campus. While his friends drool over her awesome looks and greedily snap photos of her, Issei has a sudden flashback to the last moments of his life that he remembered seeing in the dream after Amano had mortally wounded him and flown away. Mind racing, Issei decides that it was just a minor flicker of memory and ignores it, assuring his concerned friends that it is nothing as they take notice of his odd reaction to seeing the beautiful Rias.
Later in the day, Issei finds himself sitting next to his two friends as the eroge movie that Matsuda had allowed him to borrow several days ago plays on the TV. The mood in the room is surprisingly grim, considering that they are watching some quality porn, and the three of them begin to ponder as to why they still don't have girlfriends yet. Motohama recounts a rough encounter that he had with a group of girls earlier in the year, revealing how he was being taken advantage of and getting "shaken down" by the girls for the money in his pockets. Shortly after the sun sets upon the area, Issei departs from Matsuda's house along with Motohama shortly after the porn video finishes and makes his way back towards his home. Looking up at the full moon, Issei takes note of what a nice night that it is tonight, and begins getting that odd feeling of pent-up energy that he seems to be feeling whenever the sun goes down. Making his way down a darkened street, a odd, irritating feeling coming from something behind him begins to annoy him, eventually causing him to turn around to see what is causing this odd irritation. To his surprise, Issei comes face to face with mysterious man in a suit, a strange look of intrigue upon his face as he comments on just how "unfortunate" it is bumping into someone like him in this place. Unsure of what to make of the situation, the startled Issei tries to figure out just who this odd man is, but when he is asked "Who is your master?", a strong sense of panic takes hold of him and sends him into the "fight or flight" mode. Issei decides to escape from this weird man, turning around to run as fast as his legs can carry him in his attempt to escape from the suited man behind him. After running a great distance in part to the enormous amounts of energy that he gains during the night, the weary Issei comes to a halt just outside of the gates to the water fountain area of the city park, hoping that both his speed and endurance have gotten him as far away as possible from the man he encountered. Before he can catch his breath, the sound of rustling wings and the return of the same irritating feeling announces the arrival of the man from earlier, and the sight of the wings sends his mind racing back to the "dream" in which Amano sprouted similar wings shortly before brutally killing him.
Again, the winged man asks him as to just who is his master, but adds that perhaps there is the possibility that Issei is a stray. Scanning his target, the man fails to detect any traces that indicate that Issei has a current master, making note that his target is in fact a stray, which makes it much easier for him to eliminate him. Summoning the same kind of light-infused spear that Amano had used to kill him in the "dream", the fallen angel takes aim and with all of his might, hurls the spear at the panicing Issei, who hardly has time to get out of the way before the spear tears through his chest. Gravely injured, the bleeding Issei falls to his knees, grabbing the lodged spear that has gotten stuck in his chest firmly with his hands as the fallen angel approaches him, remarking on how light is a "deadly poison" for someone like Issei. With a mighty tug, the man rips the lodged spear out of his back, causing even more damage to the already battered Issei as he gasps for air, trying to hold on to whatever life that he has left. Commenting on how he seems to have missed his vital organs, the man apologizes for causing Issei such pain, and with a look of demented glee, tells him that he will kill him for sure with the next strike. Before he can land the killing blow upon the dying form of Issei, an explosion of flames engulfs the arm that holds the spear of light, injuring the angel and stopping him from carrying out the final attack. Irritated by this intrusion upon his current task, the angel looks up and comes face to face with the female who has hindered his efforts with the fire spell she used upon him. Looking up to see who is standing before him, the dying Issei is shocked to see the beautiful Rias Gremory standing before him, addressing the man who was trying to kill him moments earlier. Knowing that this girl is from the powerful Gremory bloodline of devils, the battered angel smiles and comments about leaving her servant "unattended" and vulnerable to attack, which does not impress the irritated Rias. Reminding the angel just who's jurisdiction that the city is under, Rias warns the man that if he tries to interfere again, she will have to resort to more drastic measures in order to protect what is under her authority. Holding on to his hat, the fallen angel takes to the skies, introducing himself to her as Dounashiku, and tells her that he "prays that we never meet again" as he disappears into the skies. Turning around, Rias notices her gravely injured servant and tells him that she will treat his wounds back at his house. Unfortunately for the two of them, Issei begins succumbing to the darkness of death and blacks out, sending his master into a panic.
Waking up back in his bedroom after his alarm clock goes off, the confused Issei finds himself laying completely naked upon the floor of his bedroom next to his bed. Trying to recall the series of events from the night before, Issei is certain that the odd events of the prior night were nothing more than another strange dream, similar to the one in which his "girlfriend" had killed him. Before he can come to grips with as to why he is naked, he notices something odd on his bed out of the corner of his eye and when he turns to see what it is, he is blown away to find the beautiful Rias Gremory sleeping on his bed, with not a single article of clothing upon her. Freaking out, the stunned Issei tries to recall what may have happened between the two of them the night before, and becomes enraged when he fails to remember anything that indicates that he had sexual relations with Rias in his bedroom. Taking notice of Issei's awakening, his disapproving mother heads up the stairs towards his room, demanding a good explanation for his absence and odd behavior last night. Panicing that his mother will enter his room to find both Rias and himself naked together, Issei goes into a full-blown panic attack as from behind, Rias stirs from her sleep and sits up to watch the panicing Issei with mild interest, asking if it was morning yet. Horrified, the clumsy Issei turns around to cover Rias up with a spare blanket that he had used to cover his modesty, but in the process of running over to her, his foot snags upon the blanket and sends him crashing face-first into her large breasts, just as his mother opens the door to scold him about his recent behavior. What she sees brings her to a stunned halt, as she notices her naked son laying on top of a naked woman in his room. Trying to be pleasant about this odd predicament, Rias wishes his flabbergasted mother a good morning, but her words fall on deaf ears as his mother races downstairs to tell his father about what she has just seen. Stammering wildly, she struggles to convey to her husband what she has just witnessed their son doing, and eventually she gets her point across to his stunned father. Sitting up, Issei comments to Rias that he can see her breasts, trying to stop the flow of blood oozing from his nose as he struggles to contain himself. To his surprise, she does not care if he sees them or not, and she begins to fill him in as to what happened last night, telling him that it was not a dream. Surprised that he seems to have healed remarkably fast from his serious injuries thanks in part to giving him some of her powers, Rias leans forward and tells the worried Issei that she is a devil.
Issei fought against the Fallen Angel Reynelle and her team after learning the basics of being a devil. He encounters Asia Argento while walking and helps her to get to her destination but upon nearing the place he gets a bad feelings from the holy power that it radiates with. While on one of his contracts he encounters Fried Selzen who have killed his client with a sword of light. Seeing Asia there with Freed as well. He battle Freed but is overwhelmed and severely wounded. Asia steps in front of Issei to protect him. Freed becomes angry and pins her to the wall. Following that, Rias and her servants arrive on the scene and Kiba Yuuto engages Freed in combat and overwhelms him. Fred escapes taking Asia along while the servants were restraining Issei from giving chase after him. Issei runs into Asia the next day and haves his wounds healed by her Sacred Gear Twilight Healing which can heal anyone. They go on a date but is interrupted by Reynelle who kidnaps Asia for her Sacred Gear after defeating Issei easily. Issei runs back to Rias to get help and together with the other servants Issei lead goes into battle against Reynelle and the other Fallen Angels once more. But, they arrived too late for Asia died due to the removal of her Sacred Gear. Issei chooses to fight Reynelle alone out of rage. Through will and rage he unlocked his true Sacred Gear's form Boosted Gear and with a punch cripples the fallen angel. He then allows Rias to finish Reynelle off. He begged Rias into bringing Asia back to life as a reincarnated Devil Bishop. Aisa laters attend his school Kuoh Academy and moves in with him.
After a few weeks passes by Issei is visited by Rias who askes him to sleep with her. But, they are interrupted by Grayfia Lucifer Sirzech's Queen. It's the next day while arriving at the club house that Issei meets Riser Phoenix, who's in an arranged engagement with Rias Gremory. Irritated at how Riser had started fondling another woman while engaged to Rias in his face, Issei jumps at Riser only to be one shotted by Riser's pawn. Upon waking up, Issei finds out that a rating game between Team Riser and Team Gremory will be taking place in a few weeks. He's then put through immense training by Rias and the other servants so he can learn to fight effectively. It was on this trip that he perfected his first signature technique Dress Break which will blow the clothes of anyone who is struck by it. When the Rating Game comes around, Issei and Koneko Chan are sent to secure the fields center. It was there he encountered 3 pawns and a rook. He defeated the pawns with his Dress Breaker followed by a scolding from Koneko who generally hates him for creating such a technique. He continued to assist the others in defeating nearly all of Riser's Peerage and then facing Riser himself. Though Issei then learns that because his skills were so inferior at the time that the Gear will tax his stamina at a random time and so team Gremory lost to Riser. Issei then wakes up at his house and hears from Grayfia that the others went to Riser's engagement. Sirzechs had arranged for Grayfia to send Issei to the party if he wished to face Riser once more. Issei then accept.But, he makes a pact with his the Dragon in his Sacred Gear named Draig known as the Red Dragon Emperor to obtain Balance Breaker for 15 seconds at the price of Issei's arm. He then goes to the party and challenges Riser one on one and if Issei wins riser can't marry Rias. His Balance Breaker runs out but he reveals that since he offered his arm up to Ddraig his right arm no longer fears Holy Power and punches Riser with Holy Water and a Cross delivering the finishing blow. Issei is relieved to know that only ownership of his arm is taken and not the arm itself. He then rides off on a griffon given to him by Sirzechs with Rias Gremory on his back.
Months after Issei defeats Riser, Sona Sitri the little sister of the Leviathan and president of the Kuoh Academy Student Council , brings news that Two Holy Sword Wielders have come to town. He also learns that Holy Swords are extremely dangerous to all devils. He then notices Kiba strange actions at the term Holy Sword. The two wielders show up at his house and one them turn out to be his childhood friend Irina Shidou. The next day, he learns that Irina and Xenovia have come from the holy Church to recover the stolen Excaliburs. The original shattered a long time ago but the fragments were put into new swords. The church asks Rias to not do anything to hinder their mission. Kiba then challenges them to a duel and Issei joins in to back up Kiba. But they lose to the two Holy Sword wielders without serious injuries. After the loss, Issei's notices Kiba feeling down and learns of Kiba's past from Rias. He then sets out with Koneko Chan in tow to help Kiba with his problem. They come to an agreement with Irina and Xenovia to help hunt the people whole stole the excaliburs. The group later encounters Valper Galiel head of project Holy Sword and Freed Selzen who engages in combat against the group. The two manages to escape and the devils get found out by their masters and Issei and Saji received severe punishment. Later, Irina is found injured and missing her excalibur and then is sent to Sona for healing treatment. Kokabiel one of the Grigori the Fallen Angel leaders confronts Team Gremory and challenges them to a battle with Freed Selzen and Valper Galiel. Team Gremory defeated the Cerberus monsters summoned by Kokabiel who reveals the death of God happened in the great war along with the deaths of the original Lucifer.. Kiba and Xenovia face off against Freed who wield a 4/7 Excalibur which is fused of the stolen ones. Kiba and Xenovia defeats Freed getting Issei pumped to fight. The slowly overwhelm Kokabiel together then Vali the Vanishing Dragon shows up and captures Kokabiel then hauls him off to Azazel for punishment of disobeying orders. He then greets Issei the next day and introduces himself. Issei laters receives the Dragon Slaying Sword Ascalon and fuses it with his boosted Gear from Michael leader of Angels.
After the sun sets, Issei Hyoudou gains access to several abilities due in part to the powers bestowed upon him when he was resurrected by the powerful devil Rias Gremory when she made him her newest servant. He gains access to incredible amounts of both stamina and energy when it is nighttime, his body almost quivering uncontrollably with pent-up energy for the duration of the night. However, there is one downside to being a resurrected devil, and that is the weakness and damage that the sun deals to both his energy and strength whenever he is awake during the daylight hours. The sun slowly saps away his energy until the hapless Issei is having to drag himself around the academy, severely weakened by the sun.
Though he gets over this later in the series. He also obtains various techniques with the aid of his Sacred Gear which doubles his power at will. Issei's Sacred Gear starts out as a Twice Critical which doubles his power. Through intense will power his gear evolved into it's True Form Boosted Gear which doubles his power at will or every 10 seconds. He obtains a third form Boosted Gear Sacred Supporter which allows him to boost the powers of other Sacred Gears exponentially. Next, he fused a sword for slaying dragons called Ascalon with his own gear which the blade can pop out his gauntlet and retract at any time.Next, by stealing a jewel from Vali he fused Albion's power with Ddraig to make Dividing Gear which halves the opponents power and adds it to Issei. Then, he obtains Balance Breaker. It appears in the form of the red armor he fought Riser with though this time no time limit and it's complete.