My Shadow Monarch's System - Chapter 27: Scar II.

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.

She is one of the best thieves that the world has seen in the 24th century. However, not even in her wildest dreams had she imagine that she’d be reincarnated as a good-for-nothing orphaned Seventh Miss of the Vermilion Bird Family. She finds herself stuck in a family that mistreats her, as well as an unfamiliar place with no support system.

This is the love story of the 2nd brother of the Dragon Family. He is one of the most successful businessman in the capital and one of the Emperor’s favourites – he is the most eligible bachelor in the capital and every lady in town wants to marry him.

The story starts with the female lead, Ju Mu Er, a blind teacher of guzheng, who goes to pay a visit to Long Yue to ask him to build an awning on his popular business street so her friend, a flower seller, will not get wet and fall sick. Long Yue laughs at her (because he loves money and is calculative) and she makes a bet with him that she can allow him to escape from a pesky female suitor without making it obvious.

She successfully wins the bet and from then on, Long Yue constantly makes her life a trouble (since she costs him so much money)…. not realizing he is slowly falling for her.

- Description from Novelupdates

Once I’ve become Immortal, then my attempt to conquer the world shall begin.