A teacher's murder at the hands of his student is the talk of the town. Due to the perpetrator's youth, the media censor his name and dub him "Boy A." His purported motive is simple: he disliked his teacher.

The actual identity of Boy A is Takashi Ogura, a cheerful and unassuming student, and the truth behind the events is something he will never utter. In reality, he caught the teacher raping his childhood sweetheart, Yui Sasaki, and bludgeoned the man to death to protect her. Having spent three years in a correctional facility, Takashi is out, living a normal life under a new name. But as he continues his life, the past returns to haunt him. One's sins are not easily forgotten, and the question lingers—will he forever be known only as Boy A?

[Written by MAL Rewrite]