is jujutsu kaisen episode 19 filler?

Hanami's invasion forces Tokyo and Kyoto students to fight together. Todo and Yuji partner up against the special grade, and their synergy is immediate — Boogie Woogie creates openings that Yuji fills with devastating strikes.

Yuji lands his first Black Flash, the spatial distortion that amplifies cursed energy output by 2.5 times. The moment marks Yuji's transition from brawler to genuine sorcerer.