Author's Notes: Keep in mind this is set when Yuuri doesn't know that Hippo works with the mermaids yet. And vice versa. :)

Disclaimer: I do not own Mermaid Melody. I do not own Who's That Girl? by Hilary Duff. I do not own Duff-sama. Personally, I don't really like Duff-sama that much, but this song owns.

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Who's That Girl

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There were places we would go at midnight

There were secrets that nobody else would knoww...

There's a reason but I don't know why

I don't know why, I don't know why

I thought they all belonged to me

"Hippo-san will be so happy to see me!" Yuuri said to herself happily as she swam up towards the surface. Clutched to her chest was a wrapped package with a shiny ribbon on top of it. It was presumably a present for her beau.

Who's that girl?

Where's she from?

No, she can't be the one

That you want

That has stolen my world

It's not real, it's not right

It's my day, it's my night

By the way, who's that girl

Living my life

Oh no, livin' my lifeee...

"Hippo-san! I - " The gift dropped onto the floor, along with the poor sea demon's jaw. Hippo was laughing about something while a blue-haired girl clung absolutely posessively to his arm. Sub-conciously, Yuuri found that she looked a lot like Hanon, the aquamarine pearl princess.

Seems like everything's the same around me (around me)

Then I look again and everything has changed

I'm not dreaming, so I don't know why

I don't know why, I don't know why

She's everywhere I wanna be

Yuuri's lower lip trembled as Hippo walked forward, a large smile on his handsome face. The Hanon-look-alike had detached herself from his arm, and horror was evident in her brown eyes.

"N...no...go away..." Yuuri stuttered.

"Yuuri-san? Are you okay?" Hippo attempted to touch the girl, only to have his hand batted away.

Yuuri's face was a dangerously pale shade of white. "N...no...NO! Get...get away from me!"

Who's that girl?

Where's she from?

No, she can't be the one

That you want

That has stolen my world

It's not real, it's not right

It's my day, it's my night

By the way, who's that girl

Living my life

Lines of confusion creased the boy's otherwise perfect face. "Yuuri-san! What's wrong?"

"W...who is she?!" Yuuri demanded, throwing an indignant finger towards the observing female.

Hippo found himself at a loss for words. So Yuuri thought he was cheating on her with Hanon? No way in Hell!

I'm the one who made you laugh

Who made you feel

And made you sad

I'm not sorry

For what we did, and who we were

I'm not sorry, I'm not her

"You're...not...answering," Yuuri slowly spoke after a long silence.

Closing her vivid green eyes, she forced a smile. "I see how it is, Hippo-san. And I should've realized it when we met. Anybody with such a pretty face would obviously be a heartbreaker."

Yuuri thought he had a pretty face? The thought only further flustered the poor boy; he was completely immobilized and was in no position to say anything.

Gaito's youngest fangirl turned to Hanon. "And if I were you, I'd dump him right now. He probably has more than just the two of us." She smirked, satisfied with the way her words were coming out. Perfectly fluid and languid. "But I'm not you."

Swiftly, Yuuri spun on her heel and departed.

Who's that girl?

Where's she from?

No, she can't be the one

That you want

That has stolen my world

It's not real, it's not right

It's my day, it's my night

By the way, who's that girl

Living my life

Oh no, livin' my lifeee...

"Y...Y...YUURI-SAN!" Hippo shrieked, completely terrified of what he thought had just happened.

Hanon hit him upside the head. "She's a sea demon! You moron! Do you know how hypocritical that is?! Yelling at me and Lucia for dating humans, and then you go and date a SEA DEMON! At any rate, go get her, you idiot!"

Hippo obliged, running like his legs were on fire. "Yuuri-san! YUURI-SAN!!!"

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-Dances.- I left it like that to make it angsty. No more chapters. Strictly a oneshot. -Raspberries.- HAHA.

...But of course, if enough people ask, I might make a sequel. -Looks away innocently.-