Toaru Majutsu no Index: New Testament - Volume 17, Chapter 3: Or Isolation Surpasses a Group - Engage_U.F.O.

Calamity descends upon a a tranquil world in the black of night, transforming it into a death game! This a a true apocalypse, but this is not the end of humanity!

- Description from Novelupdates

As we all know, there is a force that must not be messed with in the Southern Region, thatched cottage.

Among them, the eldest disciple is the Qingyun Sword Master of the Southern Region, with a mastery of swordsmanship.

The second disciple, the Eternal Empress, leads an era.

The third disciple is a great Confucianist in the world, and the star of Wenqu came down to earth.

The fourth disciple, the reincarnation of the demon god, suppressed Jiuyou.

…

Lu Changsheng: Me? I am nothing special, just their master.

- Description from novelbuddy

In the fantasy world ruled by Matriarchy, Kael of the Ancient Moonstone House, was working as a guild receptionist. Throughout his life, he was protected by his mother and later, younger sister, who was considered one of the highest potential individuals in the Queendom of Elyria. One day, he hears that his sister has gone missing and his family has accumulated debts of over 127 million gold coins to the Bank. The Queen comes to his rescue, paying off his debts and in exchange, he has to marry her five daughters, who each excel in a domain of their own.Having the five imperial princesses and the Queen herself as the backing, Kael has become one of the most protected individuals in the Queendom. Little did his wives know that Kael had another identity. He is the most dreaded yet noble Assassin of the imperial city, “K,” one who hunts down the criminals who escape punishment either because of insufficient evidence or using their connections.Follow Kael's journey, as he navigates his life as the protected figure in the light and protector of justice in the shadows.

The general of the demon world possessed the body of a third-rate small time celebrity. This was the story of him coming over, determined to make preparations for the demon world’s invasion of the human world, but accidentally got mixed in with the entertainment circle instead.