I, the All-Class Magus, All My Awakening Skills are LvMax - Chapter 34 --Joining Hidden Stars

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

Protagonist travels between different anime worlds to right wrongs and uncover his reason for being along the way.

“Listen up, my obedient disciple, it's time for you to descend from this mountain. Your master has arranged a marriage for you with a stunning beauty, and it's quite a steal!”With those words, the master absconded with the dowry, leaving Lin Chen feeling both aggrieved and furious. Determined, he descended the mountain to find his betrothed.However, fate had other plans, as he was waylaid on the road by a captivating woman who insisted he play the role of her fake boyfriend. To make matters even more bewildering, this woman bore an uncanny resemblance to his intended bride!

In childhood, they were neighbors. Xie Zhen always bullied Li Yu.