Demon Slayer : The Silent Journey - Chapter 122: Training pupils

Xia Yan passed through to the world of Bleach and became an eleven-year-old boy. He was rescued by Renji and Rukia in the Seireitei, and he was studying at Shin’ō Academy, and he was a student of the same class.
He is a top student of the Shin’ō Academy, and he is vying for strength by various teams. In the end, he has entered the first team of secret mobile maneuvers.
He will use punishment to kill every person who tries to threaten the martyrdom and protect his loved one.

- Description from Novelupdates

Two thousand years ago, the Emperor slayed a dragon in the wild, inaugurating the era of mankind.Since then, whenever malevolent dragons wreaked havoc, heroes have always emerged as destined, allowing time to flow across a long and peaceful human world.As the century turned, the sudden appearance of individuals with supernatural abilities triggered unprecedented disturbances. People constructed a sanctuary for these superhumans in the sky, on the back of a colossal dragon, called the Dome City.One spring day, Gongsun Ce, who had just started university six months ago, encountered a hunter who claimed to be a Wuchang master.“Hey, can you really do such a thing?!”“It's quite normal, because I am a superhuman.”—Thus, the love-comedy battle of supernatural abilities in a youthful campus begins!

The fallen ones, strange monsters that showed up on earth with the sole purpose of destroying everything and ruling over humans.Only one man remained during the onslaught, his name, was Rashin Montero.“Do you wish to live or die?”The question appeared before him.“Kill me assholes!”He died.A hundred years passed and Rashin finds himself alive in the future.It turned out he was saved by a stray angel, and was granted a powerful energy that allowed him to stand on equal footing with the monsters that once wanted to take over earth.In his new future, the world has been restored to what it ones was, a huge shield was placed around the world to keep the Hakiaas out.Heroes were summoned to defend the world against these monsters during the Countdown, while the monsters could not be killed or harmed, they could still be sent back to their world.Or at least, until Rashin arrived.[Blacksmith System activated. Welcome host.][Initializing core functions... Complete.][Congratulations, you have gained a new blue paint (Large sword.)][Stella blade has passed all requirements to evolve.][Evolving to human form can now be processed.][Congratulations, you have gained a unique core, your weapons can now undergo fusion.]Having a system that allowed him to craft weapons of all kind, Rashin enters this new world trying to survive while also remembering part of his memories.Not just that, he can also turn every weapon he makes into beautiful overpowered maidens capable of killing the Hakiaas aka fallen ones.

To Producers, the two of them couldn’t be more drastically different voice actors.