Fun game!
I like the diverse types of takodachis, each with their strengths and weaknesses.
It would be nice if the game showed a preview of the upgraded range before buying.
Also, the map is quite large and some takodachi move fast, so I had no idea where one of them had slipped and taken a life while I was focused on a different zone of the map. I would suggest adding an on-screen alert with an arrow pointing where a takodachi entered the "base", so the player can fortify the weak spot.
Good job on the game!