Disclaimer: I do not own Prince of Tennis.

A/N: I was bored and couldn't get any ideas on how to write a new chapter on the Sweet Secret. I just wrote this for fun! Enjoy~

It's another day of training in Seigaku. The team were also pumped up as their next opponent would be Rikkaidai. Oishi told them to meet up with them later when afternoon practice ends. For what reason, most people don't know.

"Man, I'm so tired. Oishi-senpai and Inui-senpai doesn't hold back at all!" Momo whined as he ran laps with Ryoma.

"Are you sure it's that or you're just mada mada?" Ryoma smirked as he sped up a bit.

"Wha- You little brat!" Momo frowned as he tried to catch up but failed to do so as he was tired.

"Mada Mada Dane."

"Hoi hoi~ Momo, you're losing to Ochibi, nya?" Kikumaru teased his kouhai as he ran beside him.

"Ah, mou. Even Kikumaru-senpai?" Momo wailed as the reply he got was laughter.

"Saa, Momo. Inui will give you a pitcher of Vegetable Juice if you let your kouhai best you like that," Fuji decided to join in the conversation with his own sadism.

"Geh. You serious? Uso!" Momo ran after Ryoma only to be left in the dust.

Momo's screams of agony were heard throughout Seigaku.

"Echizen! How dare you-" Momo angrily began as Ryoma blocked the rest of his senpai's rambling towards him.

"-and now I'm all tired for tonight! I won't be able to survive Kurumi's energy tonight!" Ryoma's ear perked up at this.

"Who's Kurumi?"

"Eh? I never told you? Kurumi is my younger sister," Momo scratched his head, "Oh yea, I never told you."

Ryoma's face said 'You don't say' while he just said, "Hm. I never expected you to be a big brother with that way you act."

"Kora! What do you mean by that?!"

"Exactly what it meant."

"Gah!"

Ryoma smirked. Who knew his senpai had a little sister? Much less, that said senpai was an older brother. He acted more immature than Ryoma himself.

"Saa, Echizen. Do you have a sister?" A certain tensai asked the freshman.

Cat-like eyes only blinked in surprise as he heard that question, "No, I don't."

"Really? I remember hearing that Momo said you have one."

"I don't have a sister," Ryoma seemed confused before realization dawned. That senpai of his must've thought that Nanako was his sister!

"Saa."

"Eh?! Echizen! Don't lie! I saw your sister with you when I picked you up this morning!" Momo shouted/complained as several heads turned to their directions.

Ryoma seemed annoyed as Momo was too loud for his liking. He can already see several people heading their way.

"Nya? What's this about Ochibi having a sister?" Kikumaru glomped Ryoma as he asked.

The freshman was surprised that he didn't struggle for oxygen. Was the redhead too interested about his cousin?

"Iie data. I never knew that Echizen had a sister."

"That's because I don't have one," The freshman announced.

"Eh?"

"Seriously? Don't try to deny it! I even saw her this morning, saying 'Have a safe trip' to you!" Momo was confused on why did his kouhai deny having a sister.

"You did see her but you misunderstood."

"Misunderstood what?"

"She's my-" As Ryoma was about to say 'cousin', Oishi's voice was heard, "Minna! Don't forget about the meeting later!".

They all responded with "Hai!" and before they knew it, Ryoma was gone along with the topic.

After his disappearance, the topic was never brought up again as they focused on the news their fukubuchou brought. They were scheduled to have a training camp and that's why our main protagonist was currently packing his clothes and necessities.

Ryoma was too focused on his thoughts about defeating a certain fukubuchou that he didn't notice he stuffed in Karupin inside his bag.

"Ah, Ryoma-san. Have you seen Karupin?" Nanako peeked in the room as the door was left open.

Her voice snapped Ryoma out of his thoughts and his attention was redirected to his bag when it began to shake. As soon as Ryoma opened it, Karupin jumped out and meowed questioningly at him.

"Karupin..." Ryoma said apologetically as he berated himself for not focusing.

"Ryoma-san, are you okay?" Nanako asked worriedly as she saw that her cousin wasn't that focused.

"...I'm okay." The green haired boy only said as he looked up to see Nanako's worried face. His thoughts traveled back to the conversation with his teammates earlier. Nanako as his older sister? She does seem like an older sister rather than a cousin to him. Not that he'd ever admit that to anyone.

"Really? You don't really seemed to be focused today, Ryoma-san..." Nanako trailed off as she saw that Ryoma was back to his own world. Once again, her voice snapped him out of his own thoughts. Damn, she knew him too well to notice his unfocused state.

"A-Aa." He uncharacteristically stuttered and inwardly cursed himself for that.

Nanako only blinked in surprise as she never heard the younger boy stutter before, "Ryoma-san? Do you want to talk about something?" She automatically concluded that something was bothering the younger boy and decided to ask.

"...Betsuni," Ryoma said before continuing, "Senpai-tachi just said something earlier. It just bugged me."

"If you don't mind, may I know what was it about?" Nanako asked as she took a seat nearby Ryoma. Karupin crawled to her lap and snuggled against her. Nanako smiled at the cat and turned her attention to her cousin.

"It was about," Ryoma paused as he debated with himself whether to say it or not. In the end, he decided to tell her, "if I had a sister."

Nanako was a little surprised by the statement. But it confused her on why does her cousin seemed to be bothered by it, "Sister? Did they think you have one?"

Ryoma nodded, "Momo-senpai thought you were my sister and announced to the tennis team that I have a sister." Momo didn't really announce it but from his loud voice, it seemed like it to the freshman.

The blue haired girl smiled softly, "Ara, Momoshiro-san thought so? I'm surprised he thought of that."

"Apparently, he heard you say good bye to me earlier."

Nanako giggled for a bit then said, "But I wouldn't mind you being my little brother."

The younger teen blinked for some seconds before turning his head away, "Hm."

Nanako smiled at that and stood up while carrying Karupin, "Ryoma-san, dinner will be ready soon."

As Nanako was about to exit her cousin's room, she felt a faint tug on her shirt and saw Ryoma.

"Call me Ryoma."

The training camp passed by and the day of the tournament finally arrived. Ryoma, who was wearing his shoes, was asked by Nanako.

"Ryoma, where is your match being held? I'll come when I can," Nanako smiled warmly at her cousin.

"It's held at-"

Nanjirou noted on how the two seems to be close. Nanako didn't add '-san' after Ryoma's name and Ryoma talked to her rather than answering in one syllable.

"Oi seishounen. You'll be late."

Ryoma glared at his father and grumbled 'I know that' before standing up, "I'm going now."

"Have a safe trip and match. Good luck." Nanako waved as Ryoma nodded back before going.

"Now then, I have to finish those chores," The blue haired girl went back to doing her chores as she happily hummed.

After a while, she finished and noted that Nanjirou went out. Probably to see Ryoma's match too. Jeez, Oji-sama can't be honest with himself.

"Game and match to Seigaku's Echizen. 7-5."

Nanako smiled as cheers of "We're the champions!" "Echizen did it!" "He did it!" filled the area. Ryoma only sighed in relief. He then looked around and saw that Nanako was in the spectators stand. Nanako smiled at him before nodding him congratulations. He smiled in thanks before pulling his cap down to hide it. Unfortunately, some people still saw it.

"Uso! Echizen smiled!" Momo shouted/announced as he saw the younger boy smile and that shocked the people around him.

"Nani?! Ochibi smiled? It's a miracle!" Kikumaru exclaimed in surprise.

"Che. Senpai-tachi is still mada mada."

After that, they lined up for the awarding of the medals. Sanada greeted them when they were packing up, "Next time, we'll meet in the Nationals. But it won't go this way in the Nationals. We'll have Yukimura."

Ryoma averted his attention back to his cousin who was still smiling at him. He turned to Fuji, "Fuji-senpai, can I just meet up with you guys later? I need to do something."

The tensai smiled, "Sure."

Ryoma nodded and grabbed his bag before heading towards his cousin. Fuji saw this and automatically concluded that the girl is Ryoma's sister.

"Saa..."

"Are, where's Echizen?"

"Over there," Fuji pointed over where Ryoma and Nanako was talking.

"Ah! That's the girl I've been telling you guys about! Echizen's sister!"

"Eh? So it's her eh~ She's pretty cute."

"Iie data."

"Good match, Ryoma. You did very well." Nanako smiled warmly at her cousin.

"Betsuni." The younger boy shrugged and pulled down his cap.

"Oji-sama also watched. I don't know why can't he be honest with us."

"He's still mada mada." Ryoma smirked.

Nanako giggled and whispered, "I see some of your teammates are interested in our conversation."

Ryoma sighed and shook his head, "They're still nosy as ever. But then they wouldn't be senpai-tachi if they weren't nosy."

"Don't you have to go?"

"It's ok. I told Fuji-senpai that I'll follow anyways."

"Ara, I'm touched." Nanako smiled playfully at her cousin.

Ryoma glared at his cousin and sighed, "I better go before they get too nosy."

"Just go home before it gets too late and be careful."

Ryoma nodded and turned to leave. Before he left, he stopped to say, "I wouldn't mind if you were my sister."

Nanako swore she saw him smile.

A/N: Well... Just a random one-shot that popped into my head? I hope you enjoyed it.