Mitsuru, a shy, reserved and introverted lad by nature, rarely speaks in front of any of his classmates. However, one day, the anti-social Mitsuru suddenly finds himself being approached by Koichi, the most popular boy in his class who asks him to be his friend.

A series of flashbacks show Mitsuru recalling his trip to the beach and camping with Koichi last summer, a memory that remains precious to them both.