To jump in, to the new world – Iori Kitahara was to take over as a student to university, to live in the uncle’s uncle’s diving shop “Grand Blue” in Izu. Sounds coming down, shining sun, cute little sister who will live together … Youth’s campus life! I was awaiting such Iori – the strongest men who did not know the scissors except the baseball fist! Early as I entered the university Iori, who had been touched by the university’s diving circle “Peek a Boo (Peek-Boo)” , Shinji Tokita and Chairman Jiro Yusui, who is a third grader, will join the fuss as a member of the circle unexpectedly. Ikemen but a disappointing geek, Kohei Imamura, who got to know himself, joins and their youth rolls steadily and steadily. Although I have a cute little cousin, Sister Oguchikawa, my sister Chisa is treated as a filthy daughter, my older sister Nana Hana is not made a partner with a heavy syscon. Iori ‘s college life surrounded by the lovable naked gidders, what will it become like ….