Pure Heart(2007)

Junjou

After coincidentally meeting his first love, Kurata, Tozaki is shocked to learn that Kurata knew about his feelings in high school. When he is drawn into a physical relationship, Tozaki can't help but fall again for his first love. However, Kurata's feelings are much more complex, and his demeanor much more stubborn. Will Kurata be able to sort out his feelings for Tozaki, or will their relationship stay at a standstill?

(Source: Bliss)