By Muses Scans:

On the summer vacation of their third year high school, Kei went to visit Koai island to meet his friend, Kou, who he have been exchanging letters with. They reunited for the first time in 12 years, Kou has plenty of friends, a complete opposite from Kei. At first, Kei is bewildered that Kou in person actually wasn’t as approachable as he was in his letters but as they share their memories together, little by little, they open up to each other. The friendship they fostered in peace changes its shape by a kiss from mere curiosity.