The story is based on a free smartphone game by Happy Elements. It was released in Japan in 2014 and is available for Android and iOS.
Happy Elements Asia Pacific
Fumitoshi Oizaki, Hiroki uchida, Hitomi Amamiya
Yumiko Kuga (Studio Jack)
Hirotoshi Arai, Sakae Shibuya, Yukiko Akiyama
Daigo Matsumura (Inaho)
Akari Saito (Graphinica)