Square Of The Moon: The Night Is Coming! (Series)

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)