Ep. 1: Six units attend the rare U4 Fes music festival despite missing return address

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The six units gather at the Unknown Underground Unbelievable Ultimate Fes, also known as U4 Fes., a mysterious music festival held once every 100 years. Happy Around! receives an invitation via mail and the four members agree to participate in the event. However, Rei observes that the invitation lacks a return address, raising questions about the source of the correspondence. This gathering marks the introduction of the units to this rare and enigmatic occasion.