At the start, I tricked the school beauty, and ended up with twins? - Chapter 76 - 75 Haidong University Will Not Shield Anyone

Three Emperors have died in quick succession. The prince whom nobody had taken notice of unexpectedly succeeds to the throne. He is quickly plunged into layers upon layers of danger. The Empress Dowager dislikes him, wishing to install a younger, more obedient Emperor. His half-brother dislikes him, accusing him of stealing the throne that is rightfully his. The palace attendants and servants dislike him, believing that he is not a true Emperor. The Child Emperor must save himself.

In this world, orphans or just anyone without any hope for this world can apply to become a “walking target”. Their sole purpose is to be a practicing dummy for the students of the sect who train to become “Demon Hunters”. These students need “walking targets” to test their training on living, walking beings of flesh and blood.
In exchange, they will be provided with food & shelter.
Their existence value is lower than a slave, but if they manage to survive a few years they can receive a life long pension.

Xiao Han is such a “walking target”. One time he witnessed a powerful Demon Hunter disposing a demon. When the demon died, a fragment of the demon that managed to escape entered Xiao Han’s heart. No one saw that, and even Xiao Han himself only felt some discomfort for an instant.

But that thing in his heart soon gave Xiao Han visions, and the first one is of a cultivation method which allows Xiao Han to absorb damage to enhance his body. A perfect cultivation method for a “walking target”.

- Description from Novelupdates

Reborn in the Naruto world, Shin Uzumaki finds himself in the doomed Land of Whirlpools. As a member of the Uzumaki Clan! Trapped in a world filled with war, betrayal, and unimaginable power, Shin’s survival seems impossible.. Until it isn’t!![Ding! Replication System Activated!][Daily Login Reward: Common Replication Card.]​​​​​​​[Newbie Gift: Perfect Sage Body—​​​​​​​Adamantine Sealing Chains​​​​​​​—​​​​​​​​​​​​​​Four Symbols Seal​​​​​​​]With the power to Copy any Ability—whether it’s the Kekkei Genkai or Rinnegan or Forbidden jutsu—Shin begins his journey to dominate the Ninja World. [First task: Save Kushina and prevent the destruction of the Uzumaki Clan.]