The Surgeon’s Studio - Chapter 2968 Extravagant surgery training (1)

Going against the heavens, Tuoba Ye reincarnated. Body concealing Divine Root, hands holding Divine Talisman, possessing previous life’s experiences, from childhood, began cultivating the most difficult body refining method: Mythical Nine Transformations.

- Description from Novelupdates

…but it seems pretty doable.

Tenjou Yuuya has been a bullied boy since the past.He lives in the home of his beloved grandfather while he goes to school. As usual, he receives a harsh bullying, and he takes an extended absence from school to have some time to heal his wounds.While on this long time of absence, he takes the opportunity to clean his grandfather’s house and goes to a room he never went before, where his grandfather keep many different objects that he gathered from his travels around the world. While he was arranging the objects, he found a door not on a wall among the objects.Out of curiosity he opens this door, what he found on the other side was…

You thought being reincarnated as an extra-side character was bad? Imagine being thrown into the body of a villain who is disowned by his own family and discarded by the author.