Ano Sora no Mukougawa

Main character starts to date his classmate Miho with the mediation of childhood friend Sayaka. Miho often looks at the sky and prays to it as if in ritual. After the first real date Miho disappears, and another girl Misa with the same surname takes her place. Misa claims that Miho died in a traffic accident while they were children. In this world only protagonist, Sayaka and friend Yuki remember grown-up Miho. Is it possible to return to the original world with Miho alive?

[From vndbreview]