Fun game! I spent about 20-30 minutes on it. Mostly played with the samurai. I liked the variety of enemies and that there were some minibosses in between that were tougher. The dialogue of the different characters was well written too.
I feel like you could actually make the combat more difficult, the player takes very little damage and oftentimes I could just stand still spamming my attacks and survive without problems. Without the fear of death it takes away from the tension of combat a little bit. I also felt like upgrades were a bit too frequent while mostly being stat upgrades which were difficult to notice. Maybe you could decrease the amount of upgrades while making them feel more impactful.
Overall a decent game, looking forward to see where it goes.