Kyoukai Senjou no Horizon – Kimitoasamade - Volume 1B, Chapter 4: Hidden Ones at a Place of Passage

Liola—the best assassin in his world—has vowed to kill no more. He was being chased by an assassination organization when he accidentally dropped into a parallel universe: through a dimensional gate and into poor teenager Kaiser’s apartment. Instead of going to the government shelter for lost dimensional travelers, Liola and Kaiser wind up going to school together.

Liola has been trying his best to live the life of an ordinary person, but after certain things happen one after the other, he begins to realize that being an ordinary person could be harder than being an assassin.

“Each betrayal leaves a scar… and hers ran the deepest.”Once, Aveline Laurent gave her heart to Damien Ashford - the man who promised her a future, only to cage her with sweet lies.She endured it all with a smile… until fate dragged her back to the very beginning.Now, with a second chance hanging by a fragile thread, Aveline returns.Not to plead, but to punish.
Not to forget, but to make him remember.But revenge is never simple. The path is fraught with shadows—and an unlikely ally–Alaric Lancaster–whose loyalties remain as mysterious as his gaze.

In a game-like world where dungeons, monsters, and players appear.

Travel to the wizarding world.

“But… what about the wizard who promised to pursue the truth?”

“Why are they all greedy people who pursue power!”

With infinite knowledge comes…

It’s endlessly weird!

- Description from novelbuddy