Double Wolf

From Shinmakoku Scanlations :

Marked by certain words, best friends Kurotani and Shirooka kissed on their high school graduation day. Moving on to the present, the two stay as friends and attend the same university. They kiss each other when given a chance, but their relationship is nothing other than kissing buddies.

Targeted and chased by girls all around, Shirooka finally snaps and drops a hint... “If none of us find a lover, I might do something more than kissing you, Kurotani."