From Manga-Heaven: Seven years ago, Amakawa Yuuto's parents died leaving him living alone without a single relative. Ever since then, his childhood friend, Kuzaki Rinko, has woken him up, cooked for him and generally taken care of him. The only thing he has left in memory of his family is a mysterious charm; a red ball given to him by his grandparents as a good luck charm (an omamori). On the day of his 16th birthday, the charm mysteriously disappears, and into Yuuto's life walks Himari: a Nekomimi-samurai girl and demon hunter who swears to protect Yuuto. There is only one small problem. Yuuto has a severe allergic reaction to cats!