Solid entry! The art-style is very cute, the music is lovely, and the sound effects are sweet. I enjoyed playing it and it's a fun wave defender for sure.
It was however not fully clear to me how the size came into play, I was guessing it had an influence on your damage, small but deadly / big but weak, but there was no real indicator of any stats, despite these stats existing behind the screens as they are used in the upgrade tab. If that was the case, the use of the prerequisite is excellent too, but it is currently unclear to me. Some visuals for these stats would be cool. I also frequently found myself accidentally clicking on upgrades as I'd be frantically clicking to defend myself as the upgrade menu came up. Maybe a confirmation button would be useful.
All in all though I really like the concept behind this game, and its execution, who wouldn't want to be a frog.