“High School Boys and the Power of Friendship” is the 8th chapter of the manga.
At Tadakuni’s house, his sister kicks him down in front of Hidenori and Yoshitake , who express shock and ask her what happened. She accuses them of stealing her underwear again, but they deny it. Incensed, she threatens to kill them multiple times and they ask her to calm down. Hidenori says that despite them being guilty the previous time, they really hadn't done anything.
The sister then calls them liars and asks them to find out who the culprit is. Hidenori says it might have been the wind, and Yoshitake is about to dismiss her as being self-conscious, when he notices Hidenori wearing her bra. He is shocked into silence.
Later, the trio are in Tadakuni’s yard behind a bush, where they are supposed to stake out the criminal. Hidenori says it’s useless, and Yoshitake notes to himself that it’s useless because he was the culprit. He then wonders what he should do as his friend, and tries to ask Tadakuni, but sees that he’s also wearing her bra. Once again, he’s shocked.
The scene cuts to Yoshitake at the riverbank at sunset. He wonders what’s gotten into the others, and whether they’re stressed out or something. He then resolves to fix the issue, deciding that he’ll ‘beat some sense into them’ and make them apologize to the sister. As he prepares to leave, however, he halts and thinks to himself if that’s what a true friend would really do.
Yoshitake is next seen in Tadakuni’s yard, where he grabs Tadakuni’s sister’s panties and pulls them on to his head. While doing so, he thinks to himself that friends always walk together and bear the sins of their comrades, as he is doing now. However, he is startled when the others burst out of the house, labelling him a pervert and the criminal. They grab him and hold him still, calling out to the sister to attack him. He tries to defend himself, but his protests are ignored. He gives up and pleads guilty to the sister, as she begins charging at him. Seeing this, he starts sweating out of fear, and eventually reveals that the others were the culprits as well, just as he receives a flying kick to the chest. Tadakuni and Hidenori curse him for his betrayal.
In order of appearance: