To conquer the otherworld dungeon that suddenly appeared in the Oosumi Strait south of Kyuushuu, an artificial island called Miyake Island was constructed. Among the adventurous divers gathered there, dreaming of striking it rich, was a Japanese man clad only in swimming trunks! His name is Kaimura Alto…… a mid-level diver who has survived countless grueling adventures—and a man who lost a gamble and pawned all his equipment. Can Alto survive his adventure with this equipment? A new kind of ocean labyrinth adventure fantasy!

Character Designer: Michihasu