Isekai Madou Koshoten: Cheat Maryoku Aru kedo, Mattari Tenin suru Koto ni Shita

The moment Earth's strongest ability holder 'hero' Takuto defeated the demon lord, he was reincarnated into another world! Luckily he was found by the goddess Kuraramela, owner of an old book store, and when he reached 14 years of age, he found himself using his ability he inherited from his past life in order to manage the book store filled with dangerous magical books. Then one day a silver haired beauty visited the store. Interested in how this Magic Academy student can be successful and lacking at the same time, Takuto accepts her request. However...