Senpai wa Otokonoko

For Makoto Hanaoka, life’s about to get more complicated. Saki Aoi, a lively girl with loads of confidence, confesses her love for Makoto one day. When he fails to reciprocate, Saki declares she will be his first love! She shares her goal with a mutual friend, Ryuuji Taiga, who also confesses his crush on Makoto. Stuck in a love triangle, Makoto must find a way to make it work and have fun.
(Source: Crunchyroll)