Shoichi Sato

A boy named Santa, born on Christmas Eve, meets Mai, a Santa Claus-in-training with an incredibly bizarre personality, on Christmas Eve. Romance blossoms.

Tasuke Shichiri is the envy of his friends because since his parents are always traveling he can do as he pleases. It's a surprise present from his father that keeps him from being lonely: an odd ring known as the shitenrin. From it comes a moon goddess named Shaorin, dedicated to protecting her "master" -- no matter how much of a mess she makes doing it! (myanimelist.net)

Millie Nocturne has one great goal in life: to be the best in the universe - at absolutely everything! But when she tries her hand at being the "best detective," she ends up an unwilling partner with two people who will change her life forever: Kane Blueriver, the psi-blade-wielding master of the starship Swordbreaker, and Canal, the smart-mouthed holographic image of the ship's computer. (myanimelist.net)

This small OVA starts with the incident at Heavenly Host Elementary School, in which three small children were killed in the school's basement. After that, it shows what the characters did the night before the incident. (imdb)

After performing a charm that would supposedly unite them as friends, a group of students are teleported to the mysterious Heavenly Host Elementary School where they are visited by the spirits of the school's murdered students. (imdb)