Supreme Harem God System - Chapter 1997 The Reward.

Over a million years ago, the first human contracted with the first Spirit. Ever since then, Spirit use has become commonplace. Humans used Spirits to carry items and start fires. Eventually, even start wars. Thousands upon thousands of years past and one day, one human did the impossible. He transcended his mortality and ascended to the realm above.

Elena, who spent her entire life as a cold-blooded female knight to avenge her family, ended up dying without claiming her revenge. When she opened her eyes she found that she went back into the past. By day she was a lady in a dress, and at night she carried a sword to change history and prevent her family’s destruction.

A legendary powerhouse of his generation, tired of the bustle of the peak, returned to the ordinary city and started a new life as an ordinary teacher. He wrote the legend in the city.

Magnificent mountains and rivers, the rising powerful ones. Some ancient martial art masters stood at the peak, becoming legendary. Some financial crocodiles rose up in the minuscule places, laughing arrogantly.

However, watching the school beauties was better than fighting and killing; educating was better than fighting for fame.

- Description from Novelupdates

This stands at the forefront of strategy guides to Life (a shitty video game)!