MTL - Conan’s World Stand-in - Chapter 49 on your face

This legend tells the tale of the protagonist, Kuroki summoned to protect the demon king from the hero.

Kuroki, unbeknownst to him, suddenly came to another world. He was summoned by the demon king, Modes. The territory which the demon king overrules was in the midst of being destroyed because of the hero. He had no choice but to bow before Kuroki.

“Please save us, Savior Dono!”

Kuroki nodded, deciding to save the demon king due to an unexpected turn of event.

A seafood chef inexplicably transmigrated into ancient times. Even though he landed in a family with a nobility rank, and theoretically was supposed to be rich, the most valuable thing in the house is a grey donkey…
Su Yu stared at the sky helplessly; in order to support the family, he could only take up his old profession and go out to sell fish.
Unfortunately, the royal family selected concubines from both genders. Even as a poor noble, he had no choice but to attend…
DISCUSSION TOPIC: Will I be selected if I display my fish-slaughtering skills?
“Meow!” His Imperial Majesty shook his tail.

- Description from Novelupdates

Long Chen traveled through the world of fantasy and became the head of the Long family.He obtained the most powerful family system.After years,When everyone was fighting for imperial weapons, every member of the Long family already had an imperial weapon!As all forces struggled to recruit geniuses, the Long family already had divine bodies, sacred bodies, Tao bodies, and children of destiny appearing frequently!With the gradual control of the worlds by the Long family, the immortal emperors and immortal kings emerged one after another and suppressed all worlds...

After breaking up with his girlfriend, he accidentally acquired a genius system and rose from there against the heavens, becoming invincible..

- Description from Novelupdates