Kaitio is the main hero of the series "Robotics;Notes." He is a third year student at Central Tanegashima High School and a member of its Robotics club.
Years ago, Kaito Yashio, along with the other passengers of the SS Anemone, unknowingly participated in an experiment by Kou Kimijima. This experiment caused all of the passengers on the ship to fall into a coma for a brief amount of time. After the incident, Kaito suffers from a spasm that is the opposite of Akiho's elephant mouse syndrome. In his case, his perception of time slows down, and it follows with state of exhaustion.
Kaito Yashio is created by 5pb, and he has no information regarding any inspiration used to create him. He first appears in Robotic;Notes visual novel game and make his first anime debut in episode 1. He is voiced by Ryohei Kimura.
Kaito often appears to be apathetic to those around him. When asked to do something, he often tells them that he will do it if they beat him at his video game, knowing that almost no one will take him up on his challenge. When the situation requires it, he will do anything to help those he cares about, especially if he is helping Akiho.
Akiho has short brownish-red hair that complements his red eyes and fair skin. He is often seen wearing his school uniform which consists of a white skirt and black pants.
Akiho Senomiya - Akiho and Kaito have been friends since childhood. Both of them experienced the Anemone-gou incident and have suffered from the same traumatic syndrome ever since. Though Kaito often acts nonchalant in front of Akiho, he does try to generally help behind the scenes.
Airi - Airi is an AI that frequently appears on Kaito's phone. She helps Kaito find her former master's reports by finding flags and explaining what has to be done for the flag to be set. Kaito seems to have become attached to Airi since he was willing to risk life and limb to protect the antenna in the radar dome.
Furugoori Kona - Furugoori or Frau is a fellow member in the Robotics Club. She first meets Kaito at an airport and since then she she has recruited him to help her ban cheater from her game, Kill Ballad.
Subaru Hidaka - Ever since Kaito had defeated Subaru during the Robo-1 competition, two have had a mutual respect for each other's robot fighting skills. Subaru even went as far as asking Kaito to join him in an international robot fighting competition as his partner.
Mizuka Irei - She is one of Kaito's friends who gives him advice or help if he eats one of her passion fruit buns. The only exception to this is when Kaito tries to search for Kimijima Reports.
As Kaito fiddles with his video game, Akiho asks Kaito to accompany her to the vice principal's office to present their club budget. Together they head over to the vice principal's office to have their budget considered for approval. At the vice principal disapproves of the enormous budgets, she decides to give Akiho a proposition. If Akiho wins the Robo-One tournament, she will consider giving Akiho the budgets she wants to enter the Robot expo.
After finding a hobby robot to enter the competition, Akiho and Kaito enlist the help of Fujita to fix their robot; they are also able to convert to the hobby robot's controller into one that is similar to the controls of Kill Ballad with the help of Furugoori Kona, the creator of Kill Ballad. With their robot completed, the two are ready to enter the tournament.
At the tournament, Kaito is easily able to reach the final round where he faces Subaru Hidaka, who is using the alias of Mr. Pleiades. With the help of his syndrome, Kaito is able to end the battle between the two in a draw and the Robotics Research club is able to get the funding they need since a student from Tanegashi high school did place first in the tournament. In addition, Kaito is able to recruit Subaru to the club by blackmailing him that he would reveal his secret identity if Subaru did not join the club.
Kaito meets a spunky blonde girl named Frau, who he discovers is the creator of Kill Ballad. Since she gave him the code for his hobby robot, Frau asks Kaito to help her find hackers in her game. At the end of the day, Kaito notices blur on his phone and what looks like a ghost walking by.
Later, Kaito returns to the school to find his missing phone. Looking through his phone, he soon discovers message that asks for a password. Then a little girl appears on his screen and Kaito discovers that the girl is the ghost that he has been looking for. The girl, named Airi, gives him a password that he enters into the bubble below the message on his phone. The message opens up to reveal a report that NASA is trying to cover up ideas that the sun is going to implode. The report also states that solar storms will have a great impact on the Earth.
The next day, Kaito returns to the school. This time he hears a sound coming from the basement. Using his IROU, he spots a message and types in the password "HiddenHand." Then he notices a cassette players and pushes the play button; the cassette players starts playing some music. Then he notices a bright lit machine; Airi explains that he is looking at the EGI system, which sends signals into space. Then Kaito asks about Kimijima and Airi, in her Geji mode, tells him that Kimijima is her master. She then tells him that Kimijima has been murdered and all relevant data about him is deleted.
One day, Kaito tells Frau that he has spasms while helping her find hackers. She, in return, tells him that her mother was the creator of Gunvarrel and that the final episode did not air on TV because all the animators had died and the director went missing. She then tells him that the director was her mother. At the end of the day, Kaito visits the Robotics Research Club's Hanger. After a few moments, the IROU of all the club members starts playing the Kagome-Kagome song. Then a woman in a black van arrives and tells the club members to get inside the van.
The club is taken to the JAXA facility and they are given an offer of support and sponsership by JAXA. However, Akiho delines the offer when the space center suggests that she should redesign the robot from scratch. Later, Kaito tries to find the second Kimijima report. To clear the flag he opens the radar dome and spends an hour clearing the other flags. Then a storm hits the island and he is forced to close the radar dome. He closes the radar dome, but almost falls to his death. Seeing that Kaito is in trouble, Airi contacts Akiho and she arrives with adults to bring Kaito to a hospital. In the report, Kaito learns that the committee of 300 plans to reduce the Earth's population and form a world government through propaganda.
Akiho is able to gather the materials needed to put the robot together and they decide to build the robot. When the robot is completed, Kaito test drives the GunBuild-1, but soon discovers that the robot does not function very well and is barely able to move one step.
The next day, Kaito finds a monopole and invites Subaru to take a look at it. Akiho tags along and Subaru speculates that the monopole could hold tremendous power. Later the club visits JAXA to negotiate a new deal. At the meeting, Subaru presents his plans on how to improve the GunBuild. Akiho disagrees with him because his plans will drastically change the appearance of the GunBuild. It is then that Kaito accidentally finds a solution when he uses his neko girl app, giving the club the idea to use the app so that people will see the Gunvarrel on their IROUs. The negotiations hits another snag when Akiho learns that a person can't pilot the robot from inside it. Later, as she broods by the GunBuild-1, Kaito visits her and ask whether she prefer finishing the GunBuild-1 or going to the expo. The next day, Akiho tells that group that she wants both options, but wants them to know that going to the expo is her primary goal.
After Kaito and Frau spend the day clearing most of the flags for the third report, She invites him and the club to a meeting to show them a new idea that she had concocted to improve the GunBuild's movements. Then after the meeting, Frau is able to clear the last flag and Kaito is able to down load the third report. The report mentions the effects of the solar storm and the companies invovled in the making of robots such as Exoskeleton. Afterward, Frau learns from an e-mail that the top ranking players on Kill Ballad Online are dead. Frau thinks this is related to her mother's death. Kaito then gets a call from Akiho and he rushes to her room. Akiho shows Kaito the leaked final episode of Gunvarrel Online; she becomes upset because the episode is not like the rest of the anime series that she has come to know.