An official spin-off series of Mairimashita! Iruma-kun, set in an alternate universe in which Iruma becomes a prominent member of the mafia.

Despite being only five years old, Iruma has seen many things as a street urchin...the most recent of which being an old man bleeding out right in front of where he lives! Ever the kindhearted boy, Iruma spends his time nursing the old man back to health and thinks nothing of it afterwards. When the old man suddenly returns, however, he reveals himself to be Don Sullivan, boss of the underground organization known as Babyls! He makes an offer to adopt Iruma as his grandson, an offer that Iruma finds himself unable to refuse...