Ane wa Tsurezure Naru Mama ni ~Otouto no Ecchi na Osewa wa Ama-Ero JK Sisters ni Omakase!~

Shimizu Taiyou is a nerd and socially awkward high schooler. For some reason, he doesn't want to get involved with anyone and spends his life immersed in a two-dimensional world. He has triplet sisters who are all high school girls. The cool and intelligent eldest daughter, Satsuki. The athletic yet naive second daughter, Chiho. The family oriented youngest daughter, Sora. One day, the sisters realize that Taiyou's lack of interest in others was due to the fact that he didn't get to be spoiled much in his childhood. So they declare that they will become his Mama in exchange! "Leave all your everyday needs, including your sexual need to us!" Like that, Taiyou's sweet and erotic life with the triplets began. [Translated and edited from the official site]