I Level Up Alone in the Princess Consort's Womb

[Every race is the protagonist's original body, not a soul transmigration, so read with confidence]

Reborn as the illegitimate child in the womb of the "Iron-Working Princess" of the Tianyue Kingdom, Lai En discovers that there are plenty of people in the harem who want to take both his and his mother's lives.

Even being born was originally just a distant hope, but Lai En awakens a System for searching, looting, and escaping in another world while still in the princess's womb.

In his first simulation, Lai En is born as a mimic monster and gains the talent to assimilate. Starting by devouring a little snail, he eventually swallows even the King of the Jungle, becoming the forest's most powerful hunter.

In the second simulation, Lai En becomes a ratman. This time he inherits all his previous talents, as well as the starting equipment granted by the System, and soon becomes the strongest rat in the nest.

After that, he simulates more and more species:

Goblins, slimes, humans, even dragons...

During one simulation, a female Sword Saint says she'll protect me for life, but I take a blade for her and die horribly in front of her.

A witch once invites me to a tea party, but I'm unexpectedly assassinated before I can go.

A kingdom's empress even wants me to be hers alone, but I end up framed and dying in prison again.

Thankfully, after countless simulations as different species, I'm already invincible before I'm even born.

Finally, one day, I am born.

But as soon as I arrive, I find the Sword Saint holding a blade to the King of Tianyue's throat.

Behind her stands the kingdom's empress, filled with lifelong regret.

"Tell me, where have you hidden him?"