It's the beginning of April and the start of a new school year. Usagi and company are now in high school and Chibiusa is planning on returning home to the Thirtieth Century since she has now completed her senshi training and is now Super Sailor Chibimoon. Usagi and Mamoru take her to the park to see her off but they're distracted by an eclipse. During the eclipse Usagi, Mamoru, and Usagi see a horned pegasus who begs for the help of a maiden. Both Usagi and Chibiusa think that they must be the maiden in question and have a row over it, but the pegasus disappears before they can argue very much. Then they see a creepy boat in the sky and they hear a weird song about the Dead Moon Circus. This is rather out of the ordinary, so they rub their eyes and when the look again the boat is gone. Well, that was surreal.
Later they go downtown and find that an actual Dead Moon Circus has set up shop. They're raffling off tickets and the general atmosphere is like a festival. Usagi and Chibiusa make cute faces at Mamoru and he buys them each a glass kaleidoscope.
Because of all the excitement, Chibiusa decides to not go home that day. Usagi points out that she's already sent a letter home telling them to expect her and everything, but Chibiusa just laughs and says that it's dated April 1, so her parents will just think it's an April Fool's joke. Mamoru rolls his eyes and can't believe Chibiusa.
Since it's her last night in town, Chibiusa and Usagi decide to stay over a Mamo-chan's. He protests at first, but he can't fight the power of the cute faces. They have a sleepover and Usagi and Chibiusa fight about which has it easier: the adult or the child. Chibiusa thinks Usagi has it the best since she's already a beautiful adult who never gets left out of anything. They also have a short conversation about how mirrors contain evil spirits, and then Chibiusa goes to sleep.
In a brief interlude, Zircona and the Amazon Quartet are introduced. They seem bad.
Meanwhile, Chibiusa dreams of the pegasus again. He calls her the maiden with the beautiful dream and takes her on a ride. They fly high over the city and she sees that Juuban is covered with an icky cloud. He then takes her home and gives her the Crystal Carillon and tells her that he will lend her his power whenever she calls. He tells her that he is the pegasus, and names himself Elios and asks for her help in return. He's trying to save some place called Elysian and mentions a Golden Crystal. Then Chibiusa catches a flash of him in a bird cage and her parents and he's gone. No more tacos after 3 am for Chibiusa.
She wakes up and finds the Crystal Carillon on her bed and she knows it was real. Then she gathers her stuff together and slips out, preparing to go back to the Thirtieth Century herself. Usagi and Mamoru wake up and find her note and both remark that they had a dream where Chibiusa was with pegasus. Hmmm. Interesting.
Chibiusa by this point is at the park looking at her kaleidescope. She admits to Diana that she doesn't want to go home, but digs in her pocket for the Time Key anyway. When she pulls it out the Crystal Carillon falls out too and she remembers the dream where Pegasus begged her to help him find the Golden Crystal and save Elysian. Her heart beats fast when she thinks about him, although she says she doesn't know if he's a friend or an enemy (although really, he doesn't seem much like an enemy, does he? How threatening is a pegasus? XD).
Chibiusa isn't sure what to do. She thinks that Elios might need her help, and then she looks into the Deep Aqua Mirror and sees the reflection of Sailor Neptune who tells her to grow into a strong soldier to help protect the princess. She doesn't know if he's truly completed her training, but she also remembers the Neo Queen telling her that she longed for the day when Chibiusa would return. She uses the key . . .
And it doesn't work. It just shocks her (literally). She drops it.
Mamoru and Usagi run up to see what's going on and find Chibiusa quite distressed. Then she sees Elios again, caged and she turns to her future parents and tells them she doesn't care if she can't go home yet. Something is going down and the pink princess feels the need to be in the middle of it.
She explains Elios's plea for help saving Elysian and for the Golden Crystal, and before they can really have an in depth powwow about it, a tiger escapes from the circus (courtesy of VesVes). Chibiusa and Usagi henshin into Super Sailor Chibimoon and Super Sailor Moon after a false start. They no longer have the power of the Grails since the outer senshi are gone, but a new power fills them up. Chibimoon uses the Crystal Carillon to call for Elios and he brings them new rods of power: the Moon Kaleidoscopes. They use Moon Gorgeous Meditation to wail upon the enemy and soon defeat it. Elios retreats and Mamoru collapses from the strain on the planet, which up until this point, he's been concealing. Who knows exactly why he's been doing this, since concealing it means that no one knows and no one can help him which just makes it worse in the long run. Oh, Mamo-chan you big noble dolt, we love you anyway.
Chibimoon and Sailor Moon crouch over the fallen Mamoru protectively, and while they do so the Amazon Quartet watch them. PallaPalla decides to grant them their earlier wish and switches their ages. Oh oh. Be careful what you wish for! Chibiusa is now sixteen and Usagi is now a very small eleven. Oh, this is wacky stuff too good for a sixties Disney movie.
Mamoru slowly comes awake to find Usagi and Chibiusa leaning over him. He is startled to see them backwards in terms of size and goggles. The girls come running up and freak when they see older Chibiusa whom they connect with Black Lady. Usagi and Chibiusa calm them down and explain that they have been switched, although they don't know how.
They take Mamoru to the hospital where he is x-rayed and they discover a shadow in his lungs which he keeps to himself again. Chibiusa and Usagi are also x-rayed, but they check out fine, they're unsure whether to take this as a good sign or a bad sign, since they still don't know what's going on. Because they don't seem as if they're going to go back to normal any time soon, Chibiusa takes charge and runs off to Usagi's house to fake something so Ikuko-mama won't get freaked out. She sends Usagi home with Mamoru.
At the Tsukino residence Chibiusa uses Luna P to brainwash Ikuko-mama into thinking she's Usagi. She goes upstairs to Usagi's room feeling a little guilty for pulling such a trick on Ikuko-mama, but there didn't seem to be much a choice. As she flops on Usagi's bed, thinking about the fact that Mamoru told her she was pretty all grown up, the Carillon falls out and Pegasus shows up. He's shocked at her new appearance and declares that she's grown and must be the maiden that he's searching for. Chibiusa hates to do it, but she corrects him and tells him that the switch came suddenly and that Luna thinks its from black magic. He tells her that he still thinks she's the maiden who can help him because she's a princess and a soldier with a beautiful dream. He mentions something about some special crystal being needed to melt the seal on the Golden Crystal then fades out again. Chibiusa wonders if she could really be the maiden he needs. Then she decides she needs to tell Mamoru that Elios has reappeared and takes off to do so.
She slows down on the way there and settles into a swing on the park. She reflects that no matter how much she loves Mamoru, he's really her papa and he belongs with Usagi. Diana tells her that she's really pretty as a grown-up and Chibiusa thinks that someday she wants to grow up for real to be this pretty and to find a prince of her own.
Meanwhile, Mercury gets attacked by her insecurities and Fish Eye who makes a pass at her. She powers up and uses Mercury Aqua Rhapsody on him. Chibiusa and Usagi show up and henshin, turning back into their original ages, and use Moon Gorgeous Meditation. Fish Eye goes blarg.
Chibimoon admires Sailor Moon because everyone can always depend on her to save the day. No one needs her with Sailor Moon around. She tells Elios (who is newly arrived) that the beautiful maiden he's looking for to help him isn't her, it's Sailor Moon. He seems to agree and she's so upset that Elios doesn't need her help that she runs off. Being an angsty pre-teen sucks ;_;
She's sure that no one needs her, so she wanders around in the rain where pegasus finds her. She asks if him if there will ever be a time where she's needed like Sailor Moon, when she's grown and beautiful. Pegasus goes up to her and gently kisses her and as he does he turns into a young boy with white hair and a big horn sticking out of his head. BINGO. Chibiusa has hit the jackpot.
Elios tells Chibiusa that she's always needed and that Sailor Moon draws her strength from having Chibiusa around always supporting her. He says that everyone is worried about her and looking for her and then tells her that there's love all around her before he fades out again. She blushes redder than a radish and her heart beats fast as she realizes that the boy was Elios as well. Wow. What a development.
A few days later, the girls, Chibiusa and Mamoru go to the Dead Moon Circus to scout around, but Chibiusa seems most intent on riding the rides with Mamo-chan. Rei goes into the House of Mirrors alone, and everyone else goes to see the show. Diana and her parents are locked outside during the performance.
Like most things in Sailor Moon, the performance is just a front for evil and it begins to brainwash the girls. Mamoru realizes that there's no exit in the circus, but can't do anything about it. Mars confronts her troubles in the hall of mirrors and then comes to save the day with a well-placed Flame Sniper. An exit appears in the circus and everyone piles out. Sailor Mars confirms that the Dead Moon Circus is definitely the evil that they've been fighting. Oooh, scary. Circus people give me the creeps.