When Ashita's parents passed away, he inherited the Tachimori Mansion which had been passed down through generations. Once a lively inn filled with many residents, the estate had recently become desolate following Ashita's loss. In honor of his late parents, Ashita endeavors to bring the mansion back to life. However, his plans are thwarted when he meets Noi, a youthful vampire, and her aide, Sesera, who claim they own the property.
Noi explains that Ashita's great-grandfather borrowed the mansion from her in exchange for its upkeep until her return. As a vampire, Noi possesses incredible strength, the ability to transform into mist, and an arsenal of spells. Her formidable dark energy attracts malevolent spirits, forcing her to constantly flee and live a nomadic life, isolated from family and companions. Despite her defenses, Ashita invites Noi and Sesera to stay with him and vows to reclaim the Tachimori Mansion's rich history alongside them.