Edit
Arthur Leywin is the main protagonist of The Beginning After The End. In his previous life, he was a king named Grey before he was reincarnated into a new world, on the continent of Dicathen.
In his former world, he lived as a king who stood on the top of his country in terms of combat, until he was presumably assassinated through poison one day. However, after living four years as Arthur Leywin, he reawoke as King Grey, as if he wasn't poisoned.
After being reincarnated into the Leywin Family, Grey decided that, unlike his previous life, he would live his life to the fullest. To be loved, and surrounded by the friends and family he was void of in his past life.