Legendary Boss, Sho

Both are japanese dramas about delinquents and include a lot of comedy. In Densetsu No Head Sho, an ordinary guy pretends to be a delinquent. In Nanba MG5, a delinquent pretends to be an ordinary guy.

The plot of Densetsu no Head Sho is very similar to Boyhood. However, in Boyhood it is a case of mistaken identity.

Both series' main characters have look-alikes, ends up exchanging places and identities. Also, both main characters have opposite personalities, one has a strong formidable strength in fights and leads an army/gang, and the other is either bullied, inexperienced or not cut out for a fight.

Both drama are about former bullied kids deciding for one reason or another to become delinquents and grow stronger. Also they all change their hair cuts because of that decision.

'Densetsu no Head Sho' might not be a BL but it's also about a guy who looks identical to the leader of a gang and finds himself temporarily taking his place!