Tensei Shitara Dai Nana Ouji Datta no de, Kimama ni Majutsu o Kiwamemasu

A magic fanatic's life came to an end after a dreadful encounter with the nobles who ended his life with a powerful spell. His last wish, being able to study and master more magic, has been answered when he was reincarnated as Lloyd de Saloom, the 7th prince of Saloom Kingdom. Being the last prince in line with no right to compete for the throne, Lloyd is basically allowed to live as he likes, allowing him to perfect his magic as he pleases...

Kodansha