Nightmare in Dreamland
Usagi's Disaster: Beware of the Clock of Confusion
Usagi to Rei taiketsu? Yume rando no akumu"
"The Sailor Guardians go to the Dream Land amusement park, where visitors have reportedly gone missing. The team splits into two groups with Rei pairing up with Usagi. But much to Rei's frustration, Usagi is more focused on playing than finding the missing people." (source)