Zoro is described as a quiet man, with a stern facade that never leaves his face. His friend; Shimotsuki Kuina, made an challenge before dying, challenging Zoro that who turns into the best swordsman in the whole world would win this challenge, unfortunately, Kuina died in an unknown accident. That left a mark in Zoro, now he's trying his best to be the best swordsman to complete her challenge and win her.