the game is very pretty and cute, I was hooked by the thumbnail !
I think it takes quite a long time to go to the final boss (as you mentioned before, having a timer could be nice, or I think just by reducing the time before the boss), personnaly it became a bit tidious to continue and wait for the boss
Moreover the climax kida fall a bit since you just have to take the pick up and do one shot, maybe having the boss to do a pattern that you have to dodge before having the possibility to land a blow ?
Nethertheless, it was a cute experiment, good job !