Under the Oak Tree (Web Novel KR) - Chapter 228

One night she gets drunk and mistakes the most well-known Mafia boss for a host and intends to sleep with him.

Oh my! What should I do? It’s best to run away!

- Description from Novelupdates

In the Abyss, all beings are imprisoned, struggling bitterly to survive. One day, in the eternally dark lower world, a young boy has a chance encounter and catches a glimpse of the upper worlds. He is fortunate to witness wonders beyond even the most beautiful dreams. Realizing there are worlds beyond his own, he refuses to settle for mediocrity and vows to ascend to the top step by step.

Satou Shiki a Japan present-day university student suddenly one day he got attacked by a slasher when he open his eyes he was already transferred to another world’s labyrinth city. In that another world he who was awakened to do a lot of “things”.

Rainer, an amateur arcanist and college student, sought to create a new spell far surpassing the magic of the few he inherited from his grandfather. Yet the interference of an unknown event during the casting of his spell led him to be thrown through space and time.