Can't remember, please help

There is this yaoi or was it shounen ai manga that the teacher thought that this boy was bullying another boy. The classmates gave him some vague answers and eventually, the teacher confronts them about it but they were actually yakuza and the uke is actually the real head in charge while the seme is acting as the fake one. The teacher decided to watch over them but ends up more or less involved with them. I appreciate it a lot if anyone can remember the name of the manga. I think it was with series of oneshots but I can't remember atm. Thanks in advance!