MTL - The Overbearing Chief Husband’s Favorite: Baby - Chapter 28 Say good duty

Xia Yan passed through to the world of Bleach and became an eleven-year-old boy. He was rescued by Renji and Rukia in the Seireitei, and he was studying at Shin’ō Academy, and he was a student of the same class.
He is a top student of the Shin’ō Academy, and he is vying for strength by various teams. In the end, he has entered the first team of secret mobile maneuvers.
He will use punishment to kill every person who tries to threaten the martyrdom and protect his loved one.

- Description from Novelupdates

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

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.

Enigmatic hands, spectral frame, and one cunning strike just like the swing of the Grim Reaper. The Supreme Assassin takes on the mystical world, and how his legendary tales sets off, progressively ascending the altar to becoming the best.

- Description from Novelupdates