Himitsu – Kuro no Chikai - Chapter 4, Part 2 – The Price of Betrayal

Dying at a young age after a disappointing life. Mat thought he hit the jackpot when he got reincarnated on a tropical island as a baby. Here, exploring mysterious lands and learning magic are a reality. The world of Elydes is beautiful and magical, wild and savage. While the Guide is impartial to all, people are not. Mat has the lowest starting point possible, and those like him rarely go far. To not let his humble birth define his life, he'll need to find the determination to grow stronger and delve into the mysteries of Elydes.

Nine Realms Sword Emperor, a legend returns, leveling everything.Genius monsters, trampled underfoot, powerful beings, wiped out with a wave of a hand.If people do not offend me, I will not offend them; if people do offend me, annihilate their entire family.

One day, I was summoned to this world.

In each world, there would be the ultimate blackened female lead called Lin Xia, and each of them would’ve drowned in the light of their first love, aka the moonlight. Unsurprisingly, all of these moonlights were beautiful, attracting the love and adoration of Lin Xia, but in each and every world, the moonlight would eventually leave in the end, ultimately causing the blackening of Lin Xia’s fragile heart.

Years later, when the blackened Lin Xia finally fell for another woman, the special memories of the moonlight which was buried deep within her blackened heart began to fade, replaced by the light of the true soulmate.

And when the memories of the moonlight faded to almost nothing, the moonlight returned abruptly, only to be rejected by the moved-on Lin Xia. Filled with a crazed sense of jealousy, the moonlight began to destroy the new couples’ lives, only to be hated entirely and finally, crushed cruelly by the angered female lead.

And this is where the story begins, as a world-hopper, Ye SangSang would complete her missions in these worlds.

- Description from Novelupdates