Summary based on seeing a "hard-translated" version:
-Rena is worried that the bunnysuit will be confiscated at baggage inspection when returning to Wildhunt
-She realizes "customized uniforms" are allowed
-Rena concludes that the best option is to simply wear it and tells Hiromi that it's her new "custom uniform"
-Hiromi declares that Rena must now wear her new "custom uniform" at all times