Kaito is a frail boy who hunts slimes on the uppermost level of the city's dungeon. One day, he finds and defeats a glowing slime that leaves behind a very special card, changing Kaito's life forever.

Kaito tries to convince his servants to let him form a different group. His new partners have big goals as well, and he needs to prepare for them.

Kaito and the girls take on floor 9 for the first time, where they're in for one nasty surprise after another.

Kaito and his friends learn the truth about Hikari's condition.