The Oniwabanshu Strike (S01E09)

Hyottoko, a member of the Oniwaban group, raids Kamiya Dojo, where Megumi is hiding. He unleashes his special attack "Fire Breath," in which he breathes fire from his mouth, onto Kenshin and Sanosuke. Anticipating the defeat of Kenshin and the others at the appearance of the powerful middle-ranked spy, Megumi tries to flee the scene, but Kaoru stops her and says "He's fighting for you," telling her to believe in Kenshin's strength. (Crunchyroll)