ぼくと彼女に降る夜 (Associated Names)

Sugamu Naito is just your average schoolboy. However, his life was changed when he was dragged into a battle between magicians called Makai Jutsushi. Naito was saved by a Makai Jutsushi girl, Yoruyomiru. His meeting with her shook his lost memories. Now that he knows the existence of dark world, he was moved by something…