My Dungeon Life: Rise of the Slave Harem - Chapter 1701

Thrown into a brutal world of swords and sorcery, his memories stolen by an unseen force, Magnus wanted only one thing: to go home.But every kingdom, devil, and god — along with regressors, possessors, and fellow reincarnators — seeks to carve him apart.Survival demands war. War demands survival.And with a System that hides more than it reveals, Magnus is dragged down a bloodstained path... one battle, one betrayal, one broken world at a time.

~ Erothyria is a world where depravity and fantasy collides ~ And this world is where Dagwood Ackley was thrust into! After picking up the rejected video game called ‘The Daughters of Eros,’ Dagwood is reincarnated into the game and is reborn as a son of Eros! But...it is impossible! No Mother is allowed to begat a son! He takes the identity; Aeric of Starlight, and gains extreme beauty and charm as the first and only ever son of the God Eros. But what is his task? Ding! [Claim all the wives and daughters of Eros] Ding! [Defeat the Goddess of Lust and Claim her!] Ding! [Build a harem of Queen Mothers and daughters and take over the Throne of Eros!] With the Celestial Depravity System, Aeric becomes the most sought after male in all of Erothyria, but he must defend this land from the evil dragons and titans, and in the end, [Claim] it all for himself!

99 is one, and nine refinements are returned to Xian.

A young town boy, stepping on Xiuxian Road, is not a family, no gold fingers, with his own determination and wisdom, the nine major cultivation system, the nine realms step by step to the peak, and finally ninety-nine one, the achievement of true immortal.

- Description from Uukanshu translation

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.