Yuji Takanashi is a university philosophy professor who can’t swim. Making awkward justifications to himself about the relationship between water and people, still he decides on the spur of the moment to enroll in a swimming class. There he encounters the teacher Shizuka Usuhara, who ignores his last-minute hesitation and enrolls him.
From that day it is one step forward and one step back for Shizuka, who finds life in the water easier than life on land, and Yuji, whose fear of water makes him a constant disturbance in class.
Gradually learning to swim brings Yuji face to face with a reality he has ignored, involving the past with his ex-wife Miyako and the future with his single-mother girlfriend Namie. There is a reason Yuji fears water, and a painful rebirth awaiting him.