The first inspiration was Made in Abyss. I liked the idea of a sort of "level" system where things got more difficult as you went.
Second was that I like running and fitness and from the magic system I had built it made me think of the ancient chilean postal runner system. I haven't been able to verify it since but I heard about it at some point when I was younger and I always liked the idea of it.
Third, was more artistically but it's varied. As I was working on and posting the comic and improving on anatomy several different things changed the way I viewed and drew my characters. I has influenced by Yusuke Murata after reading One Punch Man and then I got into more western comics and drew a bunch of inspiration from them. This was more of an amalgamation that changed my style of art drastically while I was working on it You can see the change happen in real time by reading my comic