The Water Magician (Manga): Volume 6

The mysterious rift in the dungeon turns out to be a trap! Upon activation, Abel and everyone else down in the dungeon find themselves flung to Layer 40, a level so deep that it's yet to be explored. Unfortunately for them, it is home to a passel of powerful monsters known as devils, including the most powerful devils of all-demon princes. Just as the situation grows dire, Ryo arrives in the nick of time, crashing his way through the ceiling to face off against the enemy!