Bone Collection

Bone Collection summary: Kazami, the youngest son of the esteemed Jinnai family, is a source of disgrace for his relatives as he lacks the ability to cast basic spells and combat menacing youkai despite being born into a family of renowned exorcists. Despite possessing the "Youkai Spell," which briefly empowers him with any youkai's strength, Kazami is prohibited from using it due to the strict no-interaction rule enforced by the exorcist society between races. Nonetheless, everything changes when Kazami fortuitously comes across Paira, a fascinating and charming girl from the youkai domain. After rescuing her from a treacherous youkai, Kazami breaches the ban to borrow her remarkable abilities, effortlessly vanquishing their mutual enemy. He realizes that Paira is a well-known SSS-class youkai named "Gashadokuro", yearning to become human, and Kazami's extraordinary power may help her realize her aspirations. Kazami readily agrees to aid her in transformation, even if it means getting married. It is a chance for Kazami to become the powerful exorcist he has always wanted to be, shielding the people from evil youkai. However, the newfound partnership comes with a caveat of secrecy imposed by the watchful exorcist society.