Otogiri Tobi, a 2nd grade middle school student, spends his depressing days searching for his missing older brother alongside his inhuman companion, Baku. Tobi used to rarely speak to anyone besides Baku, however one day after his classmate Shiratama Ryuuko suddenly approaches him, his life begins to change...? This is an adventure surrounding the "human" and the "inhuman" that a lone boy faces. Note: Adapted from a song and novel of the same name.