Hamidashi Eiketsu no Boukentan

The Ten'hearses Academy is a school for students who have acquired a "Secondary Name", an ability that can be activated by borrowing the power of heroes. Ryoma, who doesn't have this ability, goes on a labyrinth expedition with his party, and sees a silver-haired girl named Hilda bathing in a jungle spring. Hilda, who saved the party in the underground labyrinth, appears at the school and suddenly kisses Ryoma. This is a supernatural x adventure fantasy that unfolds in the mysterious labyrinth of the school!

(Source: Ichijinsha, translated)