Yoru ga Kuru!
English title: Square Of The Moon: The Night Is Coming!
Japanese title: 夜が来る!
Alternative titles: Yoru ga Kuru! Square of the Moon
Type: OVA
Source: Visual novel
Episodes: 4
Status: Finished Airing
Aired: Apr 25, 2002 to Feb 21, 2003
Duration: 30 min per ep
Rating: Rx - Hentai
Studios: Shinkuukan
Producers: Green Bunny
Licensors: Critical Mass Video
Genres: Horror, Supernatural, Hentai
Themes: Mythology, Super Power

Blue moon suddenly appeared near the moon, they called it True Moon. After 3 years when True Moon shined blue, a monster appeared in front of Ryo. He ran away from the monster, but finally, the monster cornered him. When he began to accept his death, a red eyed girl, Izumi, appeared. She cut the monster to death, and gone.

(Source: AnimeNfo)