Definitely a masterpiece.
This text was translated using a translation site, so the grammar may be incorrect in some places.
The combination of cute pictures and hard gameplay makes this a charming game that will attract fans of Metroidvania. Unusually for a Metroidvania game, it also has a difficulty adjustment function, so even beginners can have fun playing this game. In addition, there are a variety of stage gimmicks that entertain the player every step of the way.
There are no bad points, but if I had to pick one, it would be the fact that NPCs have hit detection. In Metroidvania games, NPCs rarely have hit detection, and I think this is more confusing for those who are familiar with the series. Of course, the fact that NPCs have hit detection is a good thing, as it allows you to play new games, such as using characters as stepping stones.
This game seems to be a demo version, but if a finished version were to be released, I'd be willing to pay for it. I'm looking forward to playing through the demo version of this game, hoping that it will also support multi-language translation. Good luck with the development!