A grimoire

Harry was very excited, but he didn't take the reward out in front of Hermione. Only after he's in a separate cabin on the train, he chose to receive the reward.

A book appeared in his hand. It looked like ancient grimoires he once saw on the stand of Flourish and Blotts, but much older. However, when reading the title, he felt like a bucket of ice-cold water was poured on his head.

"Diary of An Impregnation Abuser? What the hell is that?"

Albeit very curious, Harry knew this was neither time nor place to research. He hid the book in his trunk just in time. In the next seconds, Ron Weasley stepped in.

Harry couldn't help thinking about the book that he vaguely remembered the Sorting Ceremony and the banquet. After arriving at the dormitory and making sure the curtains were closed, he took the book out and read it under the blanket.

The book was written in Runes, a language that Harry didn't know, but somehow he could keep reading it despite not understanding the content. When Harry felt his eyelids became so heavy and decided to go sleep, a message popped up:

[You learned a new spell - Neque Curriculum]