"Ouroboros" is an ancient symbol that depicts a snake eating its own tail - meaning infinity. Based on a popular comic, a clumsy detective and a cool gang stand up to true evil. Ikuo and Tatsuya grew up in a children's orphanage together. When their favorite teacher, Yuiko, is murdered, a policeman wearing a gold watch covers up the incident. Ikuo and Tatsuya promise each other to avenge their teacher someday. Twenty years later, Ikuo is a detective in Shinjuku second police station investigating various cases with elite detective - Mizuki, while smart and handsome Tatsuya has become one of the top members of a gang group.

A young man has college and a failed business behind him. Unemployed and planning his next steps he is lodging with is mother, a small business owner. His sister and her family also move in with the two, albeit temporarily. She sees him as a loser and a lush and wants him out. She also whispers in their mother's ear to ask him to leave the house in order to find his own way and begin the rest of his life. She probably has noble intentions, but is she right and will she succeed?

Hikuma Koichi was a saxophone player, but he suffers from the after-effects of an accident. Due to that, he turned his back on music. Hikuma Koichi finds hope in the high school brass band. The band consists of problem students. Koichi struggles to instruct the brass band and to give them hope.