Zettai Unmei Houteishiki Manga

ゼッタイウンメイホウテイシキ ; 絶対運命方程式 ; 절대운명 방정식 ; Absolute Fated Equation

Tamaki, the son of a yakuza family, is friends with Tomoyuki who is 12 years older than him. One day, Tomoyuki kisses Tamaki. Tamaki becomes confused and runs away but before he has a chance figure out his feelings, Tomoyuki goes abroad for 3 years without saying anything or keeping in touch with Tamaki. Now Tomoyuki is back in Japan but he's avoiding Tamaki. Can the two become close again? Also look for Tsumasaki ni Kiss which follows the secret love of Homura (Tama’s older brother) and the heir of his rival group.