Rakuin no Monshou - Volume 7, Chapter 1: Mephius’ Melancholy

Traveling through the era of national beasts, Su Yi discovered that his pet beasts could actually choose a special evolutionary route!

When others are still trying to make the red fox evolve into a flaming fox, his nine-tailed fox fairy has already fallen in love with Liaozhai;

When others are still trying to make the thorn grass evolve into a thorn tree, his queen of thorns has already suffered from secondary school;

…

Looking at these strange beasts, Su Yi fell into contemplation.

Will I still be a beastmaster in the future?

This is the demon!

- Description from novelbuddy

Childhood sweethearts.
The most popular person in school is my childhood sweetheart.

- Description from Novelupdates

The world is terrorized by the powerful Black Witch who has been sealed in the moon. Every ten years, the night of Hexennacht arrives and a chosen witch must battle the Black Witch in hopes of finally defeating her.

As the current decade’s Hexennacht approaches, a mysterious girl named Kagami Kagami arrives and meets Horinouchi Mitsuru, the daughter of the previous Hexennacht representative.

It takes place between Kyoukai Senjou no Horizon and the City Series, two other series by the author.