My first one-shot! It's the first time I've published a story with one chapter, so it might not be good, but I've tried my best!

A note on this story: I've always thought about what would happen if someone other than Ran who knew Ran well found out Conan's identity before Ran did. This story is if Kazuha found out, and how she copes with it. This story takes place after the June 2011 London arc in the anime, so you might want to watch it to know what the 'London confession' is. This does not include the recent developments in the series past that point.

Anyways, enjoy my story, and please review!

Disclaimer: I don't own Detective Conan. If I did, then something like this might actually happen.

It had never really been apparent to her why Conan and Heiji got along so well together. She assumed it was some kind of brotherly love. But now she knew the truth: Edogawa Conan was actually Kudo Shinichi.

What startled her the most was that she knew the truth, but Ran didn't. And that scared Kazuha. What if Ran found out she knew the truth and that she'd kept it from her? Would their friendship be jeopardized? Thinking of this, Kazuha thought back to when she figured out his true identity.

Flashback

Ran, Conan, and Kogoro had been visiting Osaka yet again. They'd gone for the opening of a new detective museum, which Heiji had taken great interest in, and Conan had wanted to come too after he'd heard the great Kudo Yusaku was going to be a guest speaker. Ran and Kogoro had come to keep an eye on him, and Ran had wanted to ask about Shinichi, too.

After the whole thing was over, Heiji had taken them all to a restaurant he knew, but partway through there'd been a murder. After Heiji and Sleeping Kogoro had put on a joint deduction show, they'd stayed over at Heiji's for a night, and now it was morning, and they were taking the bullet train back to Tokyo.

Ran and Kazuha had started talking about girl stuff, and the three guys, bored, went off somewhere else. Kogoro had sat down on a bench to read the paper and to have a smoke, while Heiji and Conan disappeared somewhere.

Then Ran had gotten a phone call, looked at the display and said, "It's from Shinichi!"

She pushed the talk button. "Hello, Shinichi?"

"Ran, how've you been doing? I trust your visit to Osaka was alright."

"Yeah, it wasn't any more eventful than normal." Kazuha was listening in, in an effort to catch all the juicy stuff.

"Did you talk to Dad? I heard you went to the museum's opening."

"Yeah, I did. He said he didn't really know where you were, but he knew that whatever you were doing you had to have a good reason for to leave me alone."

"Oi! I didn't leave you alone! I sent Conan-kun to keep an eye on you!"

Ran fired up at once, "And a little boy is supposed to be a replacement for YOU! Dream on!"

Kazuha, listening, heard panting from the other end of the phone, and a sound she recognized: smothered laughter. And it wasn't just anybody's. It was Heiji's. She knew the sound from whenever he laughed at her and she sent him a death glare.

Kazuha quickly looked around, but she didn't see Heiji around anywhere, and figured he wasn't eavesdropping on Ran's conversation. That meant that if it was Heiji she'd heard, then Shinichi was somewhere nearby.

Kazuha left Ran talking to Shinichi, and walked up to Kogoro, who quickly pointed in a direction and stated that if she was looking for Heiji, to go that way. Kazuha walked around the platform, and soon spotted Heiji and Conan. They were leaning against a pillar in the middle of the platform.

Kazuha quickly looked around, but saw no sign of Shinichi. She knew what he looked like from the two times she'd seen him, and he obviously wasn't around. Then she noticed Heiji was leaning against the pillar with his cap on backwards. He was eyeing Conan and was trying not to laugh. Kazuha then realized what he was laughing at: Conan. Conan was obviously on the phone, and from his red face, she figured he was probably talking to a girl, and that was also confirmed by Heiji's laughter.

They hadn't seen Kazuha, and she went to the other side of the pillar to listen in, too. She was shocked by what she heard, and listened intently.

"C'mon Ran, don't be so hard on me! It's a really difficult case!" It was not Conan or Heiji's voice, it was the voice of a certain high school detective. Kazuha looked around cautiously, but still didn't see him around. She also noticed that there was no reply, but he talked again a minute later, and concluded that he was talking on the phone.

"Well, excuse me! I just stumbled across something interesting, and I intend on solving the case!...No I still don't know when I'll be back. The case is difficult….No I can't leave it for someone else to solve, Ran, I'm in too deeply!"

Kazuha looked around to where Conan was talking on the phone, and noticed something odd. He was holding a red bowtie between his mouth and the phone. She watched his mouth move, but she didn't hear his voice, the voice was Shinichi's.

Suddenly she heard the sound of the train's whistle in the distance. The other two heard too, and Conan/Shinichi said, "Well, it sounds like your train's coming, so I'll call you back later. Bye!" At this Conan hung up.

Heiji suddenly said, "Smooth Kudo, real smooth. You made her really mad, and Kazuha was likely by her side the whole time eavesdropping. So both of us will never hear the end of it."

"At least you can confess to your girl that you like her, Hattori, if only you had the guts to. I look like a kid, so I hardly ever see her as me, so I can't ever say it, though I came really close in London." The two started walking off, and Kazuha didn't hear anymore. She was curious about that girl Conan had mentioned Heiji liking, and hoped it was her, though she doubted it. She was around Heiji all the time, and he would've had plenty of chances to confess.

Kazuha followed them back, and silently slipped beside Ran.

"Ran-chan, how'd the rest of the conversation go? Did you confess this time?"

"No. We only argued, and I felt really bad when he hung up. The argument was partly my fault after all. I hope I didn't make him mad."

Kazuha, who'd heard the other end of the conversation, said, "You probably just made him want to come home more, and maybe a little sad. Don't worry about it. If Kudo-kun's anything like Heiji, then he probably won't even remember the argument, especially if you two argue a lot anyways."

"Thanks, Kazuha-chan." Just then the train came in, and the Mouris and Conan got on.

End Flashback

Kazuha hadn't talked to Ran since she'd left two days before. But now the secret was starting to eat at her insides, and she knew she'd have to do something. She couldn't call Ran, so she resolved to talk to Heiji about it.

After school the next day, Heiji and Kazuha were walking towards their respective houses. Heiji could tell something was bugging her.

"Kazuha, is something up?"

"…Heiji, what would you do if you knew a big secret about someone, and you didn't know who to trust with it because it might do more harm than good? But you know one of your friends also knows, but you don't know why they didn't trust you with it?"

Heiji was intrigued. "Who's the guy who knows then?"

"…Actually, Heiji, you know. I'm sure of it."

Heiji was stunned. Then he said, "Well, if you're sure I know the secret, why don't you share it with me?"

Kazuha hesitated, then she asked, "Do you promise not to call me crazy, weird, or anything else degrading should I be wrong and you don't know? And if you do know, will you promise to confess you knew all along?"

Heiji, wondering where this was going, said, "Sure. Of course I promise."

Kazuha braced herself internally, and then said, "Heiji, you know that Conan-kun and Kudo-kun are one in the same, right?" She looked right at him, registering the look of shock on his face.

Heiji, forgetting the promise he'd just made, asked, "What would give you an idea like that? It's like something out of a sci-fi movie!"

"Heiji!" said Kazuha, "you just promised not to call me crazy and to tell me the truth. So spill it."

Heiji looked around nervously and then said, "Not here. Come to my place." He then grabbed her wrist and pulled her away.

At his house, they went into the living room, after ensuring no one else was around, and Kazuha said, "Heiji, how long have you known?"

Heiji just sighed, knowing he was defeated. "Since the second time I met him. He was such a Holmes geek, he clued me in on Kudo, and when he solved the murder case later, I found him out."

"Why the secrecy, then?"

"The reason he shrunk is because he saw something he wasn't supposed to, and they tried to off him with an experimental poison. In their eyes, Kudo's dead, and that's how he wants it to stay."

"Who else knows, then?"

"His mom and dad, that crack inventor friend of his Agasa, and that little blonde girl. She's in the same boat as him."

"Shrunk you mean?"

"Yeah. She was originally a chemist, so she's been trying to come up with an antidote, but so far they're all temporary."

"So that's why Kudo-kun is always disappearing."

"Yeah, pretty much. Oh, Kazuha?"

"What?"

"Don't breathe a word about this to anybody. Not even Ran-san. The less people who know the better."

"Alright Heiji!" said Kazuha cheerfully. She knew the truth now and she would keep Conan's secret. After all, it was his to tell when he was ready.

"Anyways, I've got to tell Kudo you know. He'll have a fit, but there's no avoiding it." Heiji took out his phone and called Conan. As he predicted, Conan was furious. After a long speech about friendship and personal loyalty, Conan asked that he be allowed to talk to Kazuha.

"Toyama-san."

"Conan-kun. Or would you prefer Kudo-kun?"

"Just call me Conan-kun while I'm like this. It'll be less confusing."

"So you wanted to talk to me?"

"Yeah. How much do you know about my…situation?"

"Just what Heiji told me. He didn't go into much detail about anything, and only told me the truth after I forced him to. So don't be mad at him, it's not his fault."

"If you say so. Just don't tell Ran. She'll kill me if she finds out, especially if it's from someone else. I figure the damage will be a little less if I tell her myself. And don't tell anyone else either. Will you promise that?"

"All right, Conan-kun! Thanks for being so understanding!"
"Oh, and one more thing, too."

"Yeah, what is it?"

"Please try to get Hattori out of his habit of calling me 'Kudo' when people are around that don't know the truth. It's really irritating having to always cover that up."

"Sure, Conan-kun. I'll see you later, then!"

She gave the phone back to Heiji, and he and Conan talked for a minute before he finally hung up. Kazuha was now feeling happier, and she knew she'd be able to keep Conan's secret until he deemed the time was right to share it. After all, she knew what it was like to have a secret, and having to hide it from everyone, except Heiji, but he was clueless. Keeping secrets was old hat, and she didn't find any problems with it at all.

An OK ending, I guess. I tried to keep everyone in-character, and let me know if I screwed up in any way. As this is a one-shot, this concludes this story. I'll probably post more one-shots in the future, so look forward to them! And please review!