First, it was the legendary figure named Bjorn Ragnarsson that Kahn had heard so much about in the Zivot Empire. The fact that the man who supposedly died from the injuries after the battle with the Demon God... actually killed himself and also wiped out his soul from existence, fully knowing that he would never be able to resurrect again, whether in Vantrea or any other world... simply shook Kahn to his core.
The Demon God, in those times, being able to attach itself to a Hero's soul was also information well hidden from the world. If the 8th Hero of Darkness himself hadn't told him, Kahn wouldn't have taken it seriously.
But out of nowhere, he mentioned Miyamoto Musashi, another one of Kahn's mentors, whom he wholeheartedly accepted as his master. And now, his name was also mentioned by his predecessor.
"Do you know why his soul still exists in the Erdve Empire, and even after 600 years, he still guides the Empire of Space?" asked Morpheus.
