Yuuta is just your typical guy who enjoys an ordinary school life with his childhood friend Yuuna. Suddenly one day, a mansion appeared in his backyard, inhabited by the vampire princess Luce. One by one, other other-worldly princesses came to him, all of whom had made a childhood promise to be his bride when they grew up. He didn’t remember the promises, but then Yuuna also joined into the fray and proclaimed that she’s the one who will always be with him.

Yuuta is just your typical guy who enjoys an ordinary school life with his childhood friend Yuuna. Suddenly one day, a mansion appeared in his backyard, inhabited by the vampire princess Luce. One by one, other other-worldly princesses came to him, all of whom had made a childhood promise to be his bride when they grew up. He didn’t remember the promises, but then Yuuna also joined into the fray and proclaimed that she’s the one who will always be with him.