Who said "I'll never stop improving, not even for a second."?

This quote is attributed to Zoro.

I'll never stop improving, not even for a second. - Zoro

"I'll never stop improving, not even for a second."

Zoro Perseverance

"I am not going to die. I'm going to keep fighting until I become the world's greatest swordsman!"

"Shitty glasses."

"I don't care what the world thinks. I'm going to be the world's greatest swordsman!"

"A swordsman's true path is one of solitude."

"Perseverance is the key to success."

"Don't give up on what you believe in."

"I've been through worse."

"You learn to live with the pain."