Border Labyrinth and the Sorcerer of the Other World

When the protagonist, Theodor, is pushed into a waterway by his half-brother and wakes up, he suddenly recovers his past life's memories. However, those memories are of Kiryu Kagehisa, a Japanese man, and that he was "creating Theodor as his character in the VRMMO 'Break Force Online'". Theodor realizes that the various combat magic and techniques that Kagehisa had learned in BFO are also possessed by him. Lightly brushing off his half-brother, Theodor heads to the border city of Term Wills, where a large labyrinth exists, to create a place for himself in the world.