MTL - The Princess Wei Yang - ~ 253 heart black handcuffs

Suddenly a high school student Subaru Natsuki has been summoned to another world on the way back from the convenience store. With the biggest crisis of his life being summoned to another world and no sign of the one who summoned him things become worse when he is attacked.

The little princess of the Huo family, one of the wealthiest families, was mistakenly switched out nineteen years ago! The fake heiress is well-educated, talented, and doted on, while the real heiress is an uncontrollable girl who loves to fight, has a strange personality, and had dropped out of school very early…

In the Celestial Empire, a land ruled by Immortals and stalked by Spirits and Beasts, a young girl from the slums of an unimportant city is found to have the Talent. In the great Sect of Argent Peak, she will take her first unsteady steps upon the way.

Master said, the woman I held in my hands, I must protect for the rest of my life.

Master said, it’s hard to cultivate as a Demon, and once you enter the Demon Dao, you should never look back.

Master said, Heaven is a Circle and the Earth is a Square; that Circle represents (is) consummate perfection, and that Square represents (is) the edges and corners of one’s Heart, it’s a rebellion against Fate, a Disobedience to Heaven.

My master is named Ning Fan, he’s not a person, he’s merely a Butterfly who has entered Demonhood. He was searching for someone. No one knew who he was searching for. No one knew how long he would search for…

- Description from novelupdates