Fans Unfolding & Unshirted Boys

This must also be very "Japanese." For high school boys (as well as junior high, I hear) to show their strength and dexterity, they are made to go bare-chested onto the field and perform various acrobatic acts in pairs (carrying their partner on their shoulders, holding them as they're standing at an angle against their legs to make an airplane, etc.) The finale is this... 5 guys to one group, making the shape of a fan as it unfolds, synchronized to music and the milataristic P.E. teacher, violently signaling with a small flag which groups should be unfolding when.