MTL - Reborn with an Old Enemy on the Day of our Marriage - ~ 30. As you can see

[R18 novel with a lot of sexual content]Artem never expected to take on the role of a villain, let alone transmigrate between harem novels. Bound by a system, his task is clear: steal the heroines from all the protagonists’. From Chinese Cultivation and Korean Gate to Japanese Isekai Fantasy, VRMMORPG, and beyond—no heroine is off-limits, and no protagonist is safe!

“Finally, the owner has appeared. You read me.”The Archmage’s legacy, the Book of Truth.Binair Dalheim, a dropout of the Elfenbein Tower, accidentally discovers the Book of Truth.“I will awaken your magical talent. In return, complete me.”The dropout boy, whose dormant talent has been awakened, begins his journey to retrieve the Book of Truth as requested.

Ceres, a magic swordman who has been treated as a burden in the party, is finally dismissed by Zect, the hero and leader of the party. He realized that all of his childhood friends belonged to Zect and there was nowhere for him to stay, so he decided to go off on his own…

However, he’s actually a reincarnated person and used to be much older, so he didn’t really bear it that much when he was expelled.

And he was… well, from here on out, you’ll have to read on to find out.

Inside the 3000m underwater station, an international group of scientists and engineers live and research for possible settlement of entire human race. Park Mu-hyun, a reserved dentist joins the station in hopes for a quaint life in the deep sea. However, things quickly go south when the station gets attacked by a mysterious group of people.As the water starts to fill in the living quarters, Park Mu-hyun grabs his backpack and immediately runs for his life, but where to? Now, the peaceful station becomes the ultimate survival stage of cult madness and chaos.