Girls Saurus is a comedy / fanservice series.
Shingo Chiryū was a normal teenage boy until a large and strong obese young woman put him in the hospital after he screamed at her when she suddenly stripped and confessed her feelings for him. Now, he suffers from gynophobia and sees all women as dangerous dinosaurs. He joins the school's boxing club out of a hope he can become stronger and overcome his fears, but finds the club is mainly populated by girls. One of which is Haruka Nishiharu, the woman who attacked him.
Haruka Nishiharu was the large young woman who was in love with Shingo and the attacker who put him in the hospital when he ran away screaming from her overly aggressive confession. She was so depressed from this rejection that she threw herself into her boxing training and lost a tremendous amount of weight. At first she hated Shingo, feeling as if she was the real victim; but being around him all the time in the boxing club made her realize she still has feelings for him.
Nozomi Kanayama is a petite girl from Shingo's class who has had a crash on him since they first met. She joined the boxing club before Shingo, and was overjoyed that he became a member. She's the type of girl who will use any trick and set up any scenario she can to win Shingo's for herself.
Akira Sakō is a tomboy and upper classmen to Shingo. She hates being a girl and wants people to see her as strong. She more often doesn't wear a bra and opts for boy style briefs. She is also the daughter of a traditional and influential Japanese estate and is expected to behave as a proper lady at home. At first she wasn't romantically interested in Shingo and wanted to be close buddies, but her feelings soon started to change when she noticed that she became jealous of other girls getting his attention.
Hotaru Hoshigaoka is a new transfer student to school and is clumsy to a dangerous degree. Somehow when she trips she causes massive devastation to everything around her, but comes out relatively unharmed. She joins the boxing club to be close to Shingo, who went to such lengths to take care of her when she first arrived.
Hijiri Fusō is the lovely school nurse and sponsor of the school's boxing club. She's the only person who knows of Shingo's gynophobia and convinced him to stay in the boxing club to overcome his fear. However, she takes great pleasure in also tormenting him with his fears. She honestly believes that all men desire her and all women are jealous of her beauty.
Subaru Chiryū is Shingo's kid sister who didn't trigger Shingo's gynophobia until the girls from the boxing club dressed her up like a girl, thinking she was a bratty boy. Now dressing like a girl, people often mistake her as a teenager. Subaru idolized her big brother and still harbors her childish crush for him. She hates when it appears anyone else could take him away from her.
Shiori Tsurumai is the guarded idol of the school and is looked upon by everyone as a Madonna. She's almost always surrounded by fanatically loyal guards, but has a secret sadistic side. She fell in love with Shingo after he accidentally fell into her and kissed her. She found his look of absolute terror intoxicating, and wishes to torment him. Due to the scars over his body, she mistakes Hijiri as Shingo's dominatrix.
Tsuyoshi Arahata is a thuggish young man from an all boys school who was also attacked by the obese Haruka before she lost all her weight. Rather than being afraid, he likes her even more, because he also loves fat women more than anything. He's constantly trying to convince Haruka to go back to her plump self, and he cooks her delicious and heavy foods for her.
Misao Sakō is Akira's strict mother and current head of the powerful family estate. She rules her home as a queen that no one defies. She insists her daughter wear traditional kimonos and behaves as a proper lady. When Shingo first came to visit, she nearly forced him to marry her daughter.
Ichigo Shiogamaguchi is a gauntly thin girl who has set her eyes on Shingo after they were set up on a blind doubles date with one of Shingo's friends. She's so optimistic that she finds a compliment in nearly any insult against her. She eventually even resorts to magic to win him.