Shijō Saikyō no Mahō Kenshi, F-Rank Bōkensha ni Tensei Suru

Shijou Saikyou no Mahou Kenshi, F Rank Boukensha ni Tensei Suru: Kensei to Matei, 2-tsu no Zense wo Motta Otoko no Eiyuutan
史上最強の魔法剣士、Fランク冒険者に転生する ~剣聖と魔帝、2つの前世を持った男の英雄譚~

Source

The Strongest Magical Swordsman Ever Reborn as an F-Rank Adventurer
Shijou Saikyou no Mahou Kenshi, F Rank Boukensha ni Tensei Suru: Kensei to Matei, 2-tsu no Zense wo Motta Otoko no Eiyuutan· 史上最強の魔法剣士、Fランク冒険者に転生する ~剣聖と魔帝、2つの前世を持った男の英雄譚~
novel

Aizawa Yuri has reincarnated 2 times now and is dead tired of being the emperor of this and that. Using his skills he acquired a reincarnation artifact, and starts his life in a brand new world!

Alternative

The Strongest Magical Swordsman Ever Reborn as an F-Rank Adventurer (2024)
Shijou Saikyou no Mahou Kenshi, F-Rank Boukensha ni Tenseisuru (2024)· 史上最強の魔法剣士、Fランク冒険者に転生する
manga

Yuri was the hero who saved the world, being called “Demon Emperor” in his first reincarnation and “Sword Saint” in his second reincarnation. However, before he knew it, he was considered a “monster” and was shunned by people. Yuri finally gets fed up and decides to live 100% for himself next time. He reincarnates into the future and is immediately attacked by monsters. As he defends himself, Yuri acquires the skills of his previous lives and quickly annihilates his enemies. Eventually, Yuri arrives at the adventurers guild and decides to start his life as an F-rank novice adventurer while hiding his true strength. A different world fantasy of a man who has mastered both magic and swordsmanship begins!!