Koi o Kataranai Kuchibiru
From Hoshikuzuu Scans and Starry Sky Scans:
"Having sex without love. All the gay people do this, right?"
University student, Kawamoto has a string of one-night stands. One day, he meets a university employee called Kuroki, and he tries to bed him. "Do you always do stuff like this?" Kuroki has been in love with one of the school professors for 7 years. "I'm happy just being by his side." That unwavering dedication captures Kawamoto's heart... If love is solely loving someone, doesn't that just invite pain...?
The long-awaited young love story by Nanameguri!!