To qualify for U4 Fes., units must pass a preliminary test in which they traverse a mountain cave. After witnessing a unit be eliminated upon being trapped in a cage, Happy Around! encounters obstacles of their own like a rolling boulder, a barrage of arrows, and having to parachute after being launched from the mountain. Peaky P-key explains the traps were intended to gauge units' DJing, to Rinku's understanding and Muni's bewilderment.