Tomodachi no Nee-chan ni Koishita Hanashi友達の姉ちゃんに恋した話; I Fell for My Friend's Older Sister; A História de Quando Me Apaixonei pela Irmã Mais Velha do Meu Amigo

One day, Harusho Arisawa, a second-year junior-high boy, went over to the house of his best friend, Hisashi Misumi. That was when he meets and falls in love at first sight with Rio, Hisashi's beautiful college freshman sister. Is it just an innocent boyhood crush or...? (Source: Comic POOL, translated)