JRPG with the best "zero to hero"?

What are the best JRPG with the absolute best transofrmation from "I can narely defeat a rat" to "I am an interdimensuonal threat that eats gods for breakfast"?

I mean where the change is not just narrative, but actual gameplay, where you feel you have earned that huge difference in power.

Basically, I am trying to get a feeling similar to Tengen Toppa Gurren Lagann, where Simon starts as a nobody, and ends up piloting a mech several times larger than the universe, because eff you, that's why.

(For discussion sake, any platform is fine)

Edit: It's funny to see how some of the comments are so far from what I asked. It's like people just write their favourite games without even reading what the question was...