Fireworks squat is a pose for fireworks while keeping the long sleeves of the yukata and the buttocks off the ground.
Young people who have good core strength and can maintain their posture are praised as more attractive than fireworks.
Since ancient times, waving the sleeves and shaking the air has been a ritual to awaken the gods and inspire the soul.
The act of waving the sleeves and gently showing the palmaris longus to the other party means conveying feelings to the opposite sex, and also means attracting a good match.