So, you only have one chapter. I agree with @Dysis above that Action will be a better first genre, because it seems to target people who want to read about fighting more than the people who'd like a historic drama.
You have an emerging writing voice, with a solid grasp on grammar--that's good! You are more of a tell than show. In my world, this is fine, because I am not enamored with modern obsession over showing everything in long annoying sentences as long as the narrator has an interesting delivery. He is a bit dry, however, so injecting invectives and emotions would help.
You are on Tapas, and Tapas wants short, clear chapters. My biggest suggestion is to rearrange the first chapter by cutting back on the background, but conveying that his only goal is to make it into this fancy Japanese fighting circle and smoothly lead it to the ending where he has to fight his first opponent. Try as much as possible to keep the events chronological, as jumping between memories and present is harder to read.
The 500-1K words chapter is a norm on Tapas and they often do better than 1-1.5K chapters.
Start the next chapter with the "So, here is my opponent" and go from there.
Hope this helps.