"It's time for you to explain yourself. What do you mean, Seiren destroyed her own planet?" Nyanko asked.

The Solar Sailor Senshi had brought Mouse back to Rei's place to clarify what she had revealed to them.

"I think it's pretty self-explanatory," Mouse replied.

"No, I mean, how did she do that? We're talking about Seiren! There's no way she could do something like that…!"

Mouse turned toward Nyanko, staring at her with a dumbfounded expression.

"Are we talking about the same Seiren?"

"Huh, I think so? The airhead who's always hungry and gets distracted by everything?" Nyanko replied.

"That's just a facade. Seiren is a force of nature who was able to destroy her own planet on a whim. She's cunning and deceptive, and has no qualms in using Crow, who's just as destructive as her, in her schemes."

"What…! No way!"

"I admit this is hard to believe. Even if she did deceive us, I can't believe everything she did as Aya Reiko was all just an act," Venus said.

"Right…!"

"But, she did take an entire plane and all its passengers hostage just to get Usagi's Star Seed once," Mercury added.

"She's far from being as innocent as she pretends to be," Mars agreed.

"I guess you're right, she just had us all fooled…"

"W-Wait…! You can't seriously think Seiren is some sort of evil mastermind! What she did back then was because of the bracelets! She was being controlled by Galaxia and corrupted, just like I was!"

"Hm, I wonder about that," Neptune pondered.

They all turned towards Neptune, who was rubbing her chin with a thoughtful expression on her face.

"What are you implying?" Nyanko asked.

"Well, when you were under the influence of the bracelets, your outfit turned black," Neptune began before gesturing to Mouse, "and hers changed too, even if not as drastically as yours. And if I recall correctly, Crow's outfit also changed. For all you three, the black parts change colour. But Seiren, her outfit… it has no black on it. Even when she still had the bracelets on."

That observation was accurate. Other than Nyanko's outfit turning white to black, the black parts on Mouse's sailor uniform reverted back to being pink and lilac, while Crow's were originally dark maroon. But Seiren's outfit remained unaltered.

"So she wasn't corrupted at all, she never was!" Uranus exclaimed.

"So does that mean that… she wasn't mind-controlled by Galaxia at all? Everything she did when she was part of Shadow Galactica was of her own free will?" Jupiter wondered.

"Woah, let's calm down, okay?" Nyanko interrupted. "Even if she wasn't corrupted, her life was still in Galaxia's hands! She had her Star Seed! She could kill her at any moment by removing the bracelets! Mind-controlled or not, you can't hold it against her for obeying when she was under duress!"

"Unless she willingly joined Galaxia from the start," Pluto suggested.

"H-Hey, let's not jump to conclusions here-"

"I think it's pretty believable coming from a woman who destroyed her own planet to join Galaxia of her own volition," Mars added.

"Again, you have no proof that she actually did destroy her planet-"

"Uh, hello? I just told you she did," Mouse interjected.

"Oh yeah? And are you that sure? Did you actually see her destroy her planet?" Nyanko replied.

Mouse suddenly looked tense.

"W-Well… not exactly. Everything that happened while I was under Galaxia's control feels… hazy, like a fever dream. I remember going to Seiren's planet, Mermaid, with Crow and… someone else. Our mission was to retrieve Sailor Mermaid's Sailor Crystal. And then…"

She closed her eyes and grabbed her head.

"...Mouse?" Sailor Moon called.

"I… I can't fully remember…! Everything feels so blurry! There was a bright light, and then in a matter of seconds, no one was left alive on the planet. It was like… all the oceans had suddenly risen and turned into ice, and Mermaid was turned into a frozen desert…"

"That… does sound like Seiren's powers, but it doesn't prove it was her-"

"Galaxia said it was her," Mouse added. "And Seiren never denied it."

"Since when is Galaxia trustworthy!?"

"Please, Galaxia would never deny herself the credit for destroying an entire planet. She has no reasons to lie about Seiren doing it."

"But… she… ugh…"

Nyanko looked desperate for a rebuttal but couldn't find any. Sailor Moon really wanted to believe in her and in Seiren's innocence, no matter the odds.

"Let's try to talk to Seiren-san first and ask her for her side of the story," Sailor Moon suddenly said.

"I don't think this is a 'he said, she said' situation, it seems pretty straightforward here," Uranus replied. "Seiren is the enemy."

"I understand you want to have faith in all Sailor Senshi, but some of them are bad," Neptune added.

"Also what kind of woman brainwashes and mind-controls her own lover!?" Venus said. "As the Senshi of Love, I can't forgive that!"

"She said it was hypnotism, and she did it to protect Crow-san!" Nyanko argued.

"Nyanko-san, I understand you want to protect Seiren because you feel guilty, but you have to face the facts. She's up to no good," Jupiter said.

"Wait, feel guilty about what?" Mouse asked.

"Well, let's say that I'm kind of the reason why both of them died," Nyanko admitted.

"Oh."

Mouse paused for a moment before looking back at Nyanko.

"Welp, she's definitely coming for you first then," Mouse said. "I vote for using the Mautian as bait, and while Seiren is busy with her, we attack her from behind!"

"Hey, she's not coming for me! And we're not attacking from behind! That's cowardly!" Nyanko exclaimed.

"So no comment about being used as bait, huh," Venus said.

"I'm usually not down for that kind of tactic, but Seiren is an enemy we can't underestimate and go easy on!" Mouse replied. "If we don't stop her, who knows what she'll do to this planet? I won't let what happened to Chuu and all the planets Shadow Galactica destroyed happen to Earth! It's… the least I can do now."

"Mouse…" Nyanko whispered.

Mouse clenched her fist and closed her eyes.

"That's why I'm ready to do anything to right my wrongs! I no longer have a home to protect, and I've contributed to so many atrocities. I can't let another planet suffer the same fate. I have to stop every remnant of Shadow Galactica."

She opened her eyes, her gaze now full of determination.

"That's why I'm going to do it. Seiren is a menace and she has to go down. And I'll kill her with my own hands to stop her if I have to!"

"Mouse, wait!"

Nyanko had followed Mouse after she left the Hikawa Shrine, managing to catch up to her at the nearby park. Since it was the middle of the night, there was no one around.

"Stop following me!" Mouse yelled out, still walking.

"Please, listen to me first!"

As she said that, Nyanko grabbed Mouse by the arm to force her to stop.

"Leave me alone!"

Mouse vigorously shook her arm to break free from Nyanko's grip and then immediately pushed her away.

"What's the matter with you!? Why won't you just let me go?!"

"Because I care about you and I think what you're doing is wrong! I don't want you to have any more guilt on your conscience than you already have!"

Mouse seemed taken aback for a moment by that answer. She then shook her head and stared angrily at her.

"Stop acting like we're friends! You don't know me! You're nothing to me! So stop pretending as if you care about me, and stop bothering me already!"

Those words hurt badly at first, but Nyanko didn't let them discourage her.

"I can't! You're saying that, but I don't believe you! We got along quite well when we were amnesiac!"

"That… that doesn't count! We weren't ourselves! If I had known who you truly were, I never would have associated myself with the likes of you!"

Nyanko was starting to lose patience and get slightly annoyed.

"Is this really just about me being from Mau? Grow up! We never intended to invade Chuu! You Chuuians are just a bunch of paranoids!"

"What!? It's you Mautians that are the problem! You're just a bunch of beasts! I don't believe you! You absolutely planned to invade us…!"

"Whatever, it doesn't matter anymore, because Mau is gone!" Nyanko yelled.

"Well, so is Chuu!" Mouse shouted back.

They both went silent, realizing the magnitude of what they said. Things suddenly felt awkward. Nyanko hesitated to speak again, feeling a lump in her throat, but the silence was just unbearable.

"We… we both lost our home," Nyanko began, treading carefully. "There's no point in fighting among ourselves. We're the same… Galaxia took everything from us. And it's the same for Crow and Seiren!"

Mouse looked away for a moment, seeming hesitant.

"Maybe we are the same in that regard, and perhaps the same can be said of Crow… but not Seiren. She's a monster! She's too dangerous! For everyone's sake, I can't let her get away. She has to be dealt with."

As soon as she finished talking, Mouse turned her back, ready to walk away.

"Mouse, wait-"

"Oh my, you two are talking about me?"

Nyanko's heart skipped a beat. An overwhelming feeling of dread overtook her as she slowly turned back. Mouse seemed too paralyzed to do the same.

"And here I thought you were on my side, yet I catch you plotting against me," Seiren said with a smile, but her eyes felt empty.

"W-wait, Seiren, this isn't what you think-"

"Oh, it isn't? Because I'm pretty sure I heard Mouse-san talk about how I have to be 'dealt' with…"

"W-well, that was…"

"Unless you mean you personally have nothing to do with this and it was all Mouse-san's idea. In that case, simply step aside and I'll take this up with Mouse-san directly."

Mouse flinched but still didn't turn back. As Seiren started to walk towards her Nyanko instinctively got between them. Seiren stopped and looked down at her, sneering.

"Oh? So you do want to stand in my way after all, Nyanko-san? Even after everything you've done? You disappoint me. Aren't you ashamed?"

Nyanko clenched her teeth. She didn't want to fight Seiren, especially not after what she had done to her. But she didn't want to let her hurt Mouse either, or let them fight one another. There had to be another way. A peaceful one.

"Where's Crow-san?" Nyanko suddenly asked.

"Ugh, resting. After what those senshi did, I had to put Crow-san to sleep. I'll have a lot of work to clear her mind from all those unpleasant memories, thanks to your friends… But that's something for later. I have more pressing matters to deal with."

"Please, Seiren, let's talk this out-"

"Yeah, I don't think so."

"I won't let you do something you might regret…"

"Don't worry, I won't have any regrets," Seiren replied with a sweet smile.

"Ugh…!"

"Enough!"

Both Seiren and Nyanko were surprised to realize it was Mouse who shouted that; her back was turned from them, shivering. She took a deep breath, sighed, and raised her arm in the air, holding her brooch.

"Chuu Star Power, Make Up!"

In an instant, Mouse had transformed into her signature rodent sailor fuku. She had finally turned back.

"Mouse…!?" Nyanko exclaimed.

Before she could add anything else, Mouse pushed her aside, stepping in front of her to face Seiren.

"Where would be my pride as Sailor Chuu if I let a Mautian defend me!?"

"Mouse!?"

Seiren chuckled.

"Please, Mouse-san. Don't make me laugh. What are you expecting? You, against me?" Seiren sneered.

Mouse raised her fists.

"Aww, that's adorable. The little rat wants to fight-."

"Chuu Crunch!"

A sudden crushing blast of energy hit Seiren, sending her flying. Despite her initial surprise, Seiren managed to land on her feet.

"What…?"

"Chuu Bounce!"

"Whoa…!"

Seiren quickly dodged the second attack and smirked at Mouse.

"You missed me."

Mouse's attack hit a nearby tree and bounced on it, returning to strike Seiren right in the back.

"Ack…!"

"Chuu Bang!"

Before Seiren could recover from the last blow she got hit once again, this time by a more explosive attack.

"Agh!"

Seiren was violently propelled into the bushes.

"Whoa…" Nyanko said, in awe.

Carefully, Mouse walked towards the bushes, ready to launch another attack. But when she reached the shrubs she discovered that Seiren was nowhere to be seen.

"What the…?"

"Mouse, watch out!"

"Huh…?"

Seiren suddenly jumped from the tree above. Mouse quickly turned back but not fast enough. Seiren had seized her by the neck, lifting her from the ground.

"Aaargh….!"

Seiren was covered in minor injuries such as bruises and scratches, but nothing serious. On the other hand, she looked deadly serious, her blue eyes like ice staring at the girl she had captured.

"That wasn't very nice, Mouse-san. I was just teasing, you know? I was going to go easy on you. But you had to be so aggressive… that really hurt. If you're going to be such a threat to me and get in my way, then I guess I'll have to eliminate you too!"

On those words Seiren raised her other hand, revealing her sharp claws.

"...!"

Mouse was struggling for air, Seiren squeezing her neck even tighter.

"Seiren, stop!" Nyanko yelled. "Let her go!"

"Nyanko-san, Mouse-san… Seiren-san!?" Usagi exclaimed.

After Nyanko had left the temple to look for Mouse, Usagi had decided to go too, after realizing Nyanko wasn't coming back.

"Oh my, I wasn't expecting to have an audience. I guess this is what they call a public execution," Seiren sneered. "I'm actually pretty angry right now so I'll deal with you after-"

"Please Seiren, don't do that! Don't hurt Mouse!" Nyanko begged.

Seiren glared at her. Mouse looked like she couldn't breathe anymore.

"Tsk. You are really trying to make me look like the bad guy…"

"Seiren-"

"Hey, Nyanko-san, do you remember when Crow-san begged for my life to be spared? I'm pretty sure I got disposed of by Galaxia because of you…"

"Seiren please, I'm begging you!" Nyanko was almost on her knees.

"...And she had to watch me die because of you… I guess now you get to feel what she went through…!"

"Seiren-san, stop!" Usagi began.

"I killed Crow!" Nyanko suddenly exclaimed.

Seiren's expression turned blank. "I beg your pardon?"

"After you died, Crow actually found the true star seed you were talking about, thanks to your notebook. Very touching. I would have been even more moving if she had actually succeeded and made your death not be vain… but alas, she didn't," Nyanko taunted.

Seiren's grip around Mouse's neck seemed to grow weaker as her attention was now glued to Nyanko. Usagi and the inners just looked at Nyanko with confusion, wondering why she was provoking Seiren.

"What… did you do?" Seiren suddenly asked in a low voice.

Nyanko smirked.

"Right when she was about to get the true star seed, I double-crossed her! Ditched her in a black hole. I heard her call out your name and apologize before she died. I bet she cried too, just like when you died. Do you think dying in a black hole is particularly painful? Judging by that scream she let out, I bet it was-"

"H-Hey, Nyanko…!?" Usagi let out.

Those cruel words felt so uncharacteristic coming from Nyanko- well, ever since she had been revived and fully healed. This callousness seemed more in line with the corrupted Tin Nyanko. Usagi was worried for a second that she had reverted back to being the old Nyanko, but her doubt vanished when she took a good look at her face.

Nyanko wasn't enjoying this. Like, at all. She might be smiling, but Usagi could see it was forced. She looked tense. Even more so after she explained how Crow died. Usagi could swear there was even guilt in her eyes.

But Seiren didn't seem to notice. She looked more furious than ever. It was as if she was about to explode at any moment into a devastating tidal wave. But instead, she took a deep breath.

"You know, I assumed Crow-san was killed by somebody," Seiren began. "Be it Sailor Moon and her group, or Galaxia. And I wasn't going to hold it against them. We were enemies, after all. I would have gladly forgiven them even, as long as they didn't get in my way."

Seiren's gaze turned even colder as she continued.

"But coming from you, someone who was supposed to be an ally, I cannot forgive this. Even coming from you, I somewhat expected better. This is just so low… You're awful, Nyanko-san. This is… unforgivable!"

Seiren let Mouse slip from her hand carelessly and fell to the ground. Like a torrent, she rushed toward Nyanko and seized her by the collar.

"How about we have a little chat, Nyanko-san?" Seiren said in a threatening voice.

"Urgh…!"

"Seiren-san, don't-" Usagi tried to stop her.

But when she tried to grab her, Seiren simply tossed Usagi aside, slamming her against a tree.

"Usagi-chan!" the inners shouted.

After Usagi left the temple, they had waited for a little while before leaving too, arriving at the park a few minutes after. None of them were transformed, and Seiren was clearly taking advantage of this. They all rushed toward their princess.

"Usagi-chan, are you alright?" Ami asked.

Usagi let out a whimper, rubbing her head.

"I'm alright… what about Nyanko-san?"

The girls quickly turned back, discovering with shock that both Seiren and Nyanko were nowhere to be seen.

"Oh no, Nyanko-san…" Usagi whispered.

"Did Seiren…?" Makoto began.

"Looks like it," Rei said.

There was another grunt not so far from them. Mouse emerged from behind the bushes, gasping, struggling to catch her breath

"Where… where did Seiren go?" Mouse asked, looking around frantically.

The inners exchanged a glance.

"She… she left," Minako said.

"Not just her," Usagi added. "It looks like she kidnapped Nyanko-san!"

Mouse's attack in the manga was "Galactica Crunch" which I renamed to "Chuu Crunch" now that she's uncorrupted. I'll give you a cookie if you can guess the naming convention for the attacks I created for her ;)