Manga In Previous Life I was a Sword Emperor But now A Trash Prince

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A long time ago, a swordsman wielded the sword, living and dying by it. But, after days and months of battle, he chose to die by his own will - and was reborn as Fay Hanse Diestburg, the third prince of the kingdom of Diestburg. In an attempt to avoid the life of his past, Fay decided to lead a life of indolence, earning him the nickname of the Trash Prince. But, due to a pact with the neighboring kingdom's Afillis royal house, Fay had to go to war, leading a reinforcement army. On the battlefield, chaos ensued as the "Hero" - an entity with power that rivaled tens of thousands - wreaked havoc. Fay contemplated returning to the kingdom, but after witnessing a certain knight's death, his heart was moved and he determined to wield the sword once again. Thus began the legend of the strongest, laziest prince.