Dice In The Darkness: Cthulhu Calls - Chapter 514: Calculated

When an S-class elite assassin-raised captain of a special ops suicide squad comes home from a high-stakes Africa mission, he finds himself offered something that could potentially set him up for life- a curious assignment that he could use to finally exit his days of war and slaughter.

Then placed into a high-school setting, Lin Yi is tasked by the chairman of a top-tier multi-billion company with bodyguard duty for non-other than his own daughter, a certain little Miss of said high-school.

His enemies, once ranging from drug lords, mafia bosses, political figures, and national leaders, are soon replaced with spoiled kids who happen to have rich papas and mamas, and Lin Yi finds his intense expertise and high-threat skillset misused, and very underwhelmed…

But he does get a harem cast as diverse as his old enemies, so Lin Yi decides that, for the sake of messing around with girls as an invincible entity in a down-leveled environment, leaving his bloody and death-filled war days behind is something he’d definitely want to strive for.

- Description from Novelupdates

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.

The most feared Assassin in the world died because of vengeance.

Baek Yigang is a son of the Baek Clan, one of the seven great clans of Zhongyuan. Afflicted with the Taiyin Qi Blockage, he is cursed with a shortened lifespan and the inability to collect internal energy. He had been peacefully spending the rest of his days indoors when he was ambushed by a group of masked people. During the ambush, he lost his servant who was like a sister to him. Chased by the attackers, Baek Yigang escaped through a secret underground path. When he came across a blocked path, he decided he’d at least die fighting and picked up a rusted sword that was stuck in the ground…