Ai no Kotodama

from the back cover of vol. 1:
"After graduating from high school, best friends Tachibana and Otani decided to move-in together as more-than-friends. Although their feelings are very real, the secret nature of their relationship, and the words that have gone unsaid between them, leave room for doubt. When a chance encounter reintroduces the pair to Yuki, a former classmate, Otani becomes suspicious of Tachibana's close friendship with her. Will rumors from their high school days together spin Otani's insecurities out of control? Or could it be that Tachibana and Yuki really have rekindled an old flame?

Vol. 1 also contains two unrelated oneshots, "To the Ends of the Earth" and "Waiting for Spring" and a side story, "Sho-kun" about Tachibana's friend Shogo and his American boyfriend Al.

Vol. 2 goes back to high school when Otani and Tachibana became friends and then more. It also contains another side story about Shogo and Al, which is a continuation of their story from vol. 1.