Nira Oni is an English Ao Oni fangame. Hiroshi, Takeshi, Mika, Takuro and two new characters called Cassey and Ryan, visit an abandoned hospital, where strange things started to happen since their arrival. Hiroshi ends up separated from his friends after an incident, so he Hiroshi must find them and find a way out. But he must be careful since in that place are monsters known as oni.