First: his demon power
Second: when he killed the king he had the black feathers the demon lord had
Third: the demon lord did not have horns so implying he is not a demon he just has black wings
Forth: the demon king wanted to repeat some thing no demon would do that
Fifth: the demon king knew about the time travel magic which only the MC and his sword know works
Sixth: the demon king knew he needed the dragon heart to use the magic and knew the exact amount of magic power needed to use the magic
Speculation only don't judge.
Cue The X-Files Theme
(๑•ㅂ•)و✧
Nah, most people have already tried that in an LN discussion thread, but the consensus is no. The reason is fairly simple though - if the plot ends in a logic/time loop, there is no point to the whole story then. He will be forever repeating the same thing to fight himself. Its kinda similar to Star Trek, you will eventually write yourself into a corner.
I personally think the most probable choice to be one of the princes from the Empire, but even that has plot holes. And there is this case with the dragons. We shall see.
Following up more than 5 years later! I thought the exact same thing. Turns out, it was a nobody. Some rando with no ties to anyone. Literally ends with, "Oh, it's same was Aria" or something like that. The end.
**name
Why do I feel like the MC is the demon lord.