Tacchan (たっちゃん, Tacchan) was a popular kid and childhood bully of Garou. He is responsible for Garou's villainous and negative attitude toward heroes in his adulthood.
His only appearance is shown as a black and shadowy figure, similar to everyone else in Garou's flashbacks. However, Garou described him as being a pretty boy.
A typical bully and popular kid, Tacchan always picks on social outcasts in his class, with Garou being his frequent victim. Despite his reputation of being a bully, he is in fact cowardly since he relies on the number of his friends to take on others who tries to stand up to him, as shown when he asked two of his friends to restrain Garou.
He is also shown to be popular and charming enough to make teachers favor him, to the point of making them blind about the severity of Tacchan's actions. In the end, Tacchan proves himself to be a heartless person who cruelly enjoyed the suffering of others he inflicts on, and would use those of a lower social status and his natural charm to avoid the consequences.
Garou was a classmate of Tacchan. He would often play games where he would be Justice Man. One day while playing this game, Tacchan jumped off of a high perch and kicked a bystander with his Justice Man Kick. Garou told Tacchan that doing such things was dangerous, and in response, Tacchan chose to make him his next victim, and attacked Garou with his Justice Man Cross Chops. However, Garou got out of the way, causing Tacchan to fall. Tacchan asks Garou why he evaded his attack, complaining that he got his fingers dirty. He then tells his two friends to hold Garou down while he attacked Garou with his Justice Man Kick. He would continue to pin Garou as the monster and himself as the hero. Eventually, Garou became sick of his forced monster role and challenged Tacchan to a fight, with the conditions being if Garou won, Tacchan would leave him alone. Tacchan immediately scoffs at the idea, believing it was just a stupid hero game. Tacchan then tells his friends Sabu and Yocchan to hold Garou down, and everyone stands and watches while they all comment on Garou's supposedly ridiculous behavior and anger at the good boy Tacchan.
The bullying led to Garou's philosophy where all heroes are in it for themselves and as long as the majority favors the hero, then justice is what they decide. As Garou believes that, he has taken on the role of a monster to fight this biased justice. Ultimately, it has also led Garou to hold an image of an ideal hero of someone who can save everyone.