Everything Was a Mistake - Chapter 27

After Xia Feng transmigrated, his heart was mysteriously removed.In its place, a defective demon heart capable of sustaining life only for eighteen years was implanted.This is a magical heart that can sync with the power level of its target.To stay alive, he bound himself to the ultimate villain of the future, a Destructive Witch who was destined to destroy the world.The stronger the Destructive Witch becomes, the stronger he becomes!Thus, Xia Feng realized, it's not my fault for stirring up trouble: “Miss Witch, I admit you're strong, but not strong enough!”

Su Wan is a Realm Destroyer. She shuttles to different time-spaces using the identity of the “Cannon Fodder Ex-Girlfriend”, dedicated to plotting how to happily tear apart the male protagonist and the female protagonist. –There’s no such thing as protagonists who can’t be torn apart, only Ex-Girlfriends who don’t work hard enough~

- Description from Novelupdates

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.