Disclaimer: I'm not sure even CLAMP remember this series exists, but even so, they and Tomiyuki Matsumoto are the creators, and i can't actually claim it.
Day 1: Role Reversal
It was getting harder and harder to nail Yuki down to talk about the UFO sighting. It was as if her new crush on Sumika had made her lose sight of everything else. It just didn't make sense. Yuki was always extremely focused on her goals, but it was weird for her to change those goals so completely. After all, even after joining the Association and dedicating herself to achieving club status, she still kept a connection to the theatre.
Take today, for example. They had evidence of the UFO's erratic flight pattern, and the data the Astronomy Department had managed to collect didn't match any known aircraft. Not only that, but there were no records of any disappearances in the airspace near CLAMP School.
"Based on the evidence, it's probably safe to assume it was of extraterrestrial origin," concluded Rion.
"Why?" Yuki asked. "Are we absolutely sure it wasn't a plane? Remember, not so long ago, the University Division's weather balloon caused some very strange incidents, but it all turned out to have an entirely natural explanation."
The other Association members looked at each other. This wasn't like Yuki at all.
"Well, we'll look into that angle too, of course," Takayuki finally said, in a tone of voice that clearly meant, This has gotten out of hand.
"Oh!" Yuki shot up. "There's something i have to take care of." She darted off before anyone had a chance to add anything.
"I didn't even have a chance to talk about the deuterium," Kouji said mournfully.
Sumika was lost. As if being in a new – massive – school wasn't disorienting enough, she'd been having strange impulses lately. There was that object in the maintenance room. None of the pools she'd swum at before had a device like that to tend the water. She couldn't stop herself coming back to look at it, even after she'd nearly been hit by that laser.
A laser, seriously? It was like something out of science fiction, but even that couldn't stop her.
It was almost a relief to discover the impulses were coming from an alien that was borrowing her body. As the alien explained, there was a fugitive hiding somewhere in CLAMP School – the machine she'd seen was something it was using to convert water from the pools into fuel for its ship – and her alien was forbidden from making direct contact with Earth's population.
" . . . And your idea of avoiding direct contact with humans is borrowing the body of a teenager?" Sumika asked, just for clarification.
"It minimizes witnesses," the alien told her. "If anyone saw us, we would only seem like students. Once i've dealt with the criminal, i'll erase your memory, leaving nobody to know what happened."
"Huh," Sumika said. If even half of what she'd heard about CLAMP School's resources was accurate, they could afford to replace any amount of converted water. But the pool was her territory. It was her haven and her playing field. As if that hadn't been enough to make this fight personal, she'd been shot at with a laser.
"I'm in," she told the alien.
And so she found herself back at the Emerald Ocean in the night, diving down in the water to find the deuterium converter under the drain. She surfaced to take a breath and figure out what to do next, when a white beam of light seared through the air. Sumika instinctively kicked hard, shooting to the other side of the pool just in time. The water behind her seethed, and Sumika scrambled out of the pool.
"Lucky," a voice growled. "But i won't miss twice." The figure of her attacker came out of the shadows.
With a start, Sumika recognized her. It was the girl who'd been so impressed by her dive. "Yuki-chan!"
She felt sick. She'd thought Yuki liked her. Had she only approached her because of the alien?
"That's not really him," the voice in her head said unnecessarily. "He's under the control of the alien i'm after."
"Her," Sumika corrected out loud, as if that were the most pressing part of the situation. "She is."
"Cute," said the voice. "But that's a boy."
"No, she really isn't. I've talked to her. But what do we do?"
"You die," the alien in Yuki's body informed them, leveling the pistol it carried at them. Sumika lunged to the side, just barely evading the laser that shot at her.
"Battle armor on," she exclaimed in unison with the alien inside her head. Brass armor appeared out of thin air, clamping down on Sumika's body over her racerback.
The alien in Yuki hissed in surprise. "Who are you?"
"I'm Outer Space Milky Way Police Force Officer No. 192!" Sumika's alien declared in her voice. "And you need to let Yuki-chan go," Sumika added. "She's–"
The alien in Yuki cackled. "Oh i know! She's in love with you! That'll make it all the sweeter when she's the one to kill you."
"That's what you think," the Space Police Officer replied. "By Milky Way Space Law Article 1, Number 28, you are forbidden from making contact with unapproved species of any primitive planet's civilization. Do you–"
"Shut up!" the alien in Yuki screamed, starting to run. It tossed its laser gun into the other hand. A blade of light, humming like electricity, emerged from Yuki's right arm.
Sumika caught the alien's swing, deflecting it on her vambrace. "I won't let you!" she exclaimed through gritted teeth.
Yuki's face grinned at her, but she couldn't imagine the real Yuki making a feral expression like this. "This body fell for you," the alien crooned, "and now you'll be the one to fall."
Sumika didn't have a chance to think of a comeback, and the Space Police Officer didn't bother with one. "Eraser Blade!" A blade of red light rose out of Sumika's palm. "Eraser Z Beam!"
The red beam, on voice command, sheared through Yuki's body. Sumika couldn't hold back a scream as Yuki fell to her knees, then toppled slowly forward. Sumika dropped down herself to catch her.
"She's unharmed," the voice in her head was quick to assure her. Apparently the alien had given up on misgendering Yuki. "I extracted the fugitive into a stasis pod. The host will regain consciousness in time."
"Good," said Sumika vaguely. Yuki really wasn't cut in half, she realized as if from a distance. The alien was right. Whatever that beam was, it hadn't done any physical damage. She checked for a pulse, and then Yuki's breathing. Satisfied, she sat back with a sigh. It was all over.
A/N: Not sure why i decided to make the space cop mildly transphobic – it was probably a dig at TokyoPop's translation consistently refusing to use the right pronouns for Yuki, even with the dialogue and narrative making it very clear she's a girl, even from characters who have no way of knowing she was AMAB, even from characters who know her well enough to know how she identifies. Even the alien who was inside Yuki's head called her a boy. Give me a break. The point is, Yuki is a canon trans wlw, and that's beautiful. This reversal was a ton of fun to write, but thanks to the weather i'm a day late and a story short as usual.