Thaddeus Greywall

Originally a 29-year-old office worker from Japan, he got hit by a truck and died, then got reincarnated into the world of Syrenica, a fantasy world of swords and sorcery. He was reborn in the powerful and wealthy nation of Hylandrica as Thaddeus Greywall, firstborn son and heir of Archduke Tobias Greywall, a retired S-rank adventurer nicknamed "The Ice Lord". It's been 12 years since his rebirth, but he still remembers his previous life. As a result, he is surprisingly mature for a 12-year-old, as well as being unfailingly polite, charming, and kind. A rookie adventurer in his own right, he uses his ice magic and swordsmanship to help anyone in need, wanting to be worthy when he eventually inherits from his father. (You can be either a native of this world or another reincarnated person. You choose your own name, age, race, appearance, and abilities. It's a fantasy setting, so go nuts. Have fun!)