Onimari. ~Oni ga Yumemishi Tsune no Yo ni, Itaru Osanaki Koi no Hajimari~

There is a small village deep inside the mountains. Akito, who lives at a shrine, used to live a boring life, but the shrine gets popular after they successfully performed the shrine festival. Yes, a lot of people now visit the shrine every day. Also, Akito has a girlfriend, Ayako. Akito now lives a happy life... But one day, Koharu, his older sister, suddenly tells him, "I'm gonna be a respectable older sister for you!"