Itsuka Koi ni Naru made

Chiaki and Kazuma have been brought up like brothers, but as they get older, their relationship starts to change. One night, when Chiaki's staying over, Kazuma is woken by strange sounds coming from the futon next to him, only to find Chiaki touching himself... Kazuma offers to help him out, and his touch confuses but excites Chiaki. As they touch one another, Kazuma sees a look on Chiaki's face he's never seen before... After they come down from their high, Chiaki avoids Kazuma's gaze because he doesn't want Kazuma to see how flushed he is, and also because he's finally realized his true feelings for his friend. Following on from that day, the two of them touch each other like it's some kind of game...

(Source: Renta!)