Imaginary Vol. 3 by Niiro Ikuhana

Back when Tasuku was a kid, he harbored a secret: he was in love with his friend Maika. But Maika moved away for school before he could gather his courage and confess. Now, as adults, they've reconnected as friends, and being together brings back memories of their shared past. It was so easy to fantasize about wild things when they were children, but what has become of those fantasies now that they've grown up?
Binding: Paperback / softback