Manjiro Sano/Synopsis

History
Ever since he was a child, Mikey was under the care and tutelage of his martial arts master grandfather. As a result, he underwent rigorous martial arts training and was recognized as a genius. He lived with his grandfather and brother together in the former's dojo.

Sometime around elementary school, Emma Sano came to live with the Sano family. The two eventually formed inseparable sibling bond.

In fifth grade, Mikey meets Draken when the latter was instructed by older children to bring him to them so he could get beaten up. Mikey takes an interest in Draken and agrees to go meet the older kids. Upon meeting them, Mikey immediately executes a flying kick to the leader's face and breaks several of his teeth. Mikey then nonchalantly invites Draken to hang out with him instead, to which the latter happily agrees to.

In Mikey's first year of middle school, he and some friends decide to form a gang, naming it Tokyo Manji Gang.

Toman arc
Mikey and Draken visit the fights organized by Masataka Kiyomizu. Mikey is initially shown to be quite carefree and informal, but upon his reception by the audience becomes more aloof. Despite reactions from the crowd, Mikey does not acknowledge any of them, instead approaching Takemichi Hanagaki. After being introduced, Mikey gives him the nickname of Takemitchy, and decides that from that point onward the two will be friends. Draken and Mikey then break up the ring, declaring that underground fights are not permitted in Touman.

The following day, Mikey and Draken come to Takemichi's classroom. Hearing that Takemichi was being kidnapped, Hinata Tachibana runs after them. Upon meeting Mikey, she slaps him in the face and attempts to leave with Takemichi but is stopped by Draken. Mikey says he is going to kill the two, but Takemichi protests, and asks him to forgive Hinata. Mikey prepares a punch, but then says that he was only joking, and that he would never hurt a girl. Takemichi, Mikey and Draken then leave peacefully, and Hinata apologizes, saying she misunderstood the situation. Mikey accepts, but reprimands her, saying that her actions could've been bad if he was a dangerous person and calls her a nice girl, telling Takemichi to take care of her. The group bikes to a river and Mikey mentions that he likes Takemichi because he reminds him of his older brother of 10 years, who had died. He states that he wishes to create an era of delinquents like the one his brother was a part of, and asks Takemichi to assist him.

Shibuya Arc
In year 2018, new alternate timeline, he hailed in Manila, Philippines to escape the authorities. Only Takamichi found him there alone in the abandoned building. There, he met his end after the attempted (fake) murder by Naoto's hand.