Ryuuko Aiutsu Diamonds Cut Diamonds

Synopsis

One night, brash blonde high school student Toraji went to a party with his childhood best friend, Ryuunosuke. At the party, they both got lucky and ended up having a threesome with a cute girl. However, in the heat of the moment, Ryuunosuke leaned over the girl's shoulder and kissed Toraji deeply! What's a yankee boy to do when he realizes his best friend is in love with him?! (Source: Tokyo Mangasha, translated)