Shinwa Densetsu no Eiyuu no Isekaitan  

神話伝説の英雄の異世界譚, The Mythical Hero's Otherworld Chronicles

In another realm called Aletia, Hiro was once summoned and served as Mars, the God of War. Along with his companions, he saved the land and expanded its borders to form an expansive empire. Afterward, he chose to return to his own world, taking only his memories with him. Despite enjoying contentment in his new life, fate brought him back to Aletia once more after a millennium had passed. In this revived world, the past glory of Aletia was reduced to myths. Meanwhile, a young hero emerged as the Dual Black Hero King, opening up a fresh chapter in the Mythical Legend series.

Shinwa Densetsu no Eiyuu no Isekaitan has been published digitally in English as The Mythical Hero's Otherworld Chronicles by J-Novel Club since December 1, 2022.