Douyara Ore wa Imadoki Gal na Toshiue Osananajimi kara Gekiomo Kanjou wo Mukerareteiru Rashii

Yuito Kujou discovers that his childhood friend Suzuno Yuuki, with whom he had an unrequited love, is actually in love with his older brother. Being constantly compared to his older brother is something he has become quite used to, but he's not quite ready to give up. Meanwhile, Suzuno's older sister Kano Yuuki, a gal college student, begins directing intense feelings at Yuito!

(Source: Takeshobo, translated)