Kai

Kai is a Mod-Soul.

Personality
He is loyal to his fellow Mod-Souls, as continuously calling them his "friends" despite the fact they had tried to kill him.

Dark Souls
Kai borrows the form of Rin Tsubokura and tries to take the other Mod-Souls, but they turned into Hollows. Ichigo Kurosaki saves him and brings him to the Human World, but Kon said he was already gone.

Trivia
"Kai" is the name Kon said he wanted when Ichigo named him, as both names are derived from "Kaizō Konpaku."