The spinoff follows Ryuunosuke Akutagawa, who vows revenge on a man dressed in black in order to rescue his sister. However, as he is about... more>> to starve to death, a man from the Armed Detective Agency appears. <<less

The manga is based on the spinoff light novel of the same title and explores the past of the characters Osamu Dazai and Chuuya Nakahara.