Iori Kitahara relocates to the coastal town of Izu for his freshman year at the local university, settling into an apartment above Grand Blue, a scuba diving shop owned by his uncle. Iori harbors high hopes and dreams of an ideal college experience, but upon entering the shop, he is drawn into the alcoholic antics of the carefree Diving Club members who frequent the establishment. Persuaded by upperclassmen Shinji Tokita and Ryuujirou Kotobuki, Iori reluctantly joins their bizarre party. His cousin Chisa Kotegawa later walks in and catches him in the act, earning Iori her utter disdain. Based on the popular comedy manga by Kenji Inoue and Kimitake Yoshioka, Grand Blue follows Iori's misadventures with his eccentric new friends as he strives to realize his ideal college dream, while also learning how to scuba dive.