Imouto-kei Kyonyuu no Shinyuu ga Kanojo no Iru Ore wo Yuuwaku Shite Kita

One day, Hiro received a request from Yui, a friend of his girlfriend Akari. Her request was all about letting her be his "girlfriend" for just one day. He refuses because he doesn't want to betray Akari, but Yui's seduction leads him around by the nose, following his lust... (Source: Melonbooks, tr