First Manga Appearance: Chapter 25
Name Meaning: Toshi=town, Yuki=going to, Sae=even, Jimae= taking care one's responsibilities by oneself
Gangs: Kamakura Mad Dogs; Oni-baku Gumi
Homeroom Class: 1-D; 1-F (repeated)
Current School: Tsujido High School
Previous Schools: Kamakura P. S. 5
Penis Size: Giant tortoise
Notable Features: Scary, Yakuza-like face
Attended Kamakura P.S.5 with his friend, Kamata & gained fame in during 8th grade. Becoming arrogant from their newfound fame, they got beaten on the street by some 9th graders & went after them for revenge, attacking them one by one. He first used pencils as a weapon on the 9th grader's leader. They were widely feared after that incident. After graduating, he attends Tsujido High with Kamata.
After a period of suspension for fighting at school, he returns to Tsujido with Kamata & begins targeting the Oni-baku after hearing of their strength. They attack all those in league with the Oni-baku, including Tsukai, Abe & Makoto. After capturing Ryuji, he manipulates Makoto into betraying Eikichi, leading him into an ambush. However, he is attacked from behind by Makoto, who remains loyal to the Oni-baku, during his fight with Eikichi. He is eventually beaten by Eikichi, while Kamata is beaten by Ryuji. The Kamakura Mad Dogs accept defeat & befriends the Oni-baku.
He later hears about the Oni-baku's plan to get laid with Itou Yui & her friends & invites himself, much to the Oni-baku's dismay. He convinces Kamata to come, but is denied. He & the Oni-baku Gumi compete for the new blonde girl, Kaoru, revealed to be Kamata's sister. He beats up Kamata & pursues Kaoru & remains the final 2 in the competition, along with Eikichi. Eikichi eventually beats him & claims Kaoru for himself. He finds out Kaoru's secret the following day from Kamata.
During the Fumiya arc, he is one of the 1st Tsujido student to get targeted by Fumiya's Kyokuto High. He is able to take on a restroom full of Kyokuto students but is attacked from behind by Maruyama, a previous victim of his pencil nose attack, who returns him the favor by shoving pencils up his nose. They are interrupted by Fumiya, who smashes his nose into the ground, breaking it. He is taken to hospital after Ayumi & Mariko find him lying in a pool of his own blood. He & Kamata later escape to aid Ryuji against Fumiya, only to find Fumiya has already been beaten.
During the Okubo arc, his head gets smashed into the table by Okubo, injuring his nose, when he defends Eikichi. After finding out Eikichi's decision to give in to Okubo's threats, he & Makoto head off to confront Okubo on their own, despite Eikichi's protest. They get beaten easily & are saved by Eikichi. The fight is postponed by Otsupo, who tells Okubo not to fight Eikichi when he is injured. He arrives to backup Eikichi after Okubo ambushes the injured Eikichi, not complying with the agreement. He stops a crazy Eikichi from killing Okubo, who is beaten to near death.
He offers Makoto money after hearing of Makoto's girlfriend, Mami's pregnancy & assists him against Mami's father, who disproves of the marriage. He helps fight of Mami's father's men, allowing Makoto & Mami to escape, until Mami discovers that she isn't really pregnant. Sometime later, he finds that his girlfriend, Hiromi, has been cheating on him, petrified to break up with him due to his scary face. He is approached by Kikuta Noriko, who asks him to pretend to be her boyfriend & scare off a stalker. After getting beaten by the stalker & his friends, he follows them & takes out his revenge.
He is held back a year & ends up in the Oni-baku's class, 1-F, in which the homeroom teacher is the brutish Minamino Youka. He plans to ambush Minamino with Eikichi & Abe but abandons the idea upon seeing Minamino's brute strength. He accompanies Eikichi & Abe to Minamino's previous school, the Yushin Institute & discovers his secret, in which they use against him. He & the Oni-baku Gumi is later targeted by the 1st years in 1-F, known as the K. T. Butai but easily defeats them with Kamata. The K. T. Butai's leader, Katsuyuki, turns out to be the Oni-baku's friend & is beaten up for causing trouble.
During the Idaten arc, he arrives as backup with the rest of the Oni-baku Gumi during Eikichi's fight with Takezawa, preventing the Idaten gang from attacking Eikichi. He later gets introduced by Moro Hiro to the awesome psychic powers of Kiyoma from Tsujido with Kamata & Tsukai. He beats up Kiyoma upon finding out its lmitations, annoyed that a big deal has been made of it. During the Midnight Angel, he goes looking for Ryuji & is attacked by Akutsu, who takes his address book & finds out Ryuji's sister's apartment.
He later backs up Ryuji with the Oni-baku Gumi to prevent Akutsu's Midnight Angel from fighting dirty. They instead clash against Kamishima & the Kamakura Massacre Unit, part of a plan by Akutsu for the 2 gangs to take each other out. Struggling to fend off their opponents, they are attacked from the darkness by Midnight Angel & the fight is interrupted by the police. Sometime later, he steals Katsuyuki's Kawasaki Zephyr & changes the colour to pink. He sells it for a cheap price to a foolish Makoto, causing all sorts of trouble between Katsuyuki & Enoshima High.
During the Yokohama Calvary arc, he goes to Yokohama searching for Kamata upon hearing about his problems with the Yokohama Calvary, chiding Kamata for not talking to him even though they were friends. He gets attacked by the two Yokohama Calvary leaders, Nakagaki & Mauchi, getting a light bulb shattered in his mouth. He gets dragged back to Ryuji's bus & gets involved in the fight between the Yokohama & Shonan gangs, of which is broken up by the police. He later arrives to backup the Oni-baku's fight against the Yokohama Calvary along with the other Shonan gangs.
He uncharacteristically starts bawling upon hearing of Kamata's decision to leave for America & continues to bawl as he sees Kamata off at the airport. After Kamata's departure, he recruits Kiwamezawa Usagi of Kamakura Ryokuryo High, a large man whose face is even scarier than his own, as the new Kamakura Two. He uses Kiwamezawa to take on the Oni-baku & reclaim Tsujido. He & Eikichi apologise to each other after Eikichi summons Minamino to fight Kiwamezawa & the fight goes out of control. During the feud between Eikichi & Ryuji, he sides with Ryuji in an attempt to pay Eikichi back for last time.