Riku

Riku is a student Minagawa Jousuke saved from the extortion of Kawabuchi.

Plot
Riku is first introduced in Atsushi Tanzawa's flashback, protecting his girlfriend from Kawabuchi and his posse. As Riku attempts to mitigate the bleeding of his broken nose, Kawabuchi threatens to hurt his girlfriend if he does not he does not relinquish his wallet. Before Riku can respond, Minagawa Jousuke intervenes and effortlessly knocks Kawabuchi unconscious.

After Riku thanks Jousuke for saving them, Jousuke pulls him aside and tells him that he must sacrifice his pride in order to protect his girlfriend if they ever encounter a similar situation in future. Riku smirks and agrees.