Jibaku-kun is the main Spirit of the series. Unlike the other eleven Spirits, Jibaku does not have any distinguishing features from the others, he is simply bald and does not wear any type of adornment. Jibaku also does not have any special powers and, like all Spirits, he causes a huge explosion when he opens his hands.

Jibaku is the Spirit of the Great Child of the 1st world, Primas. Before becoming the Spirit of Baku, Jibaku belonged to En, who was looking for a successor so that he could become a Great Soldier in World Zero. Although Jibaku is in constant conflict with Baku, they both respect each other a lot and he always gets embarrassed when he is praised or recognized by Baku.