(This is a little something I came up with while listening to Excuse me, I'm Sorry (Japan's character song). One of the lines was "My straight black hair, will be blonde by tomorrow" or something like that. So I decided to write everyone's reactions! Enjoy)

The world summit was minutes from starting and nearly all nations where present, except Japan. "Veh~! I wonder Japan is?" Veneziano sighed staring at the door absent-mindedly. Romano nudged his brother in the ribs keeping him awake. Germany looked over to China who was wearing a concerned expression. "You usually arrive with him China! Why was today different?" The German asked.
"He called me earlier saying he was going to be late and to go ahead!" China explained. The other nations looked at each other. It was unlike Japan to be late to anything, especially something as important as the world summit. As they decided to start without him, the door slowly opened. "I apologise for being so late!" Japan slipped through into the room and every Country gasped. His once jet black hair was now blonde like America's! "Veh~! Ja-Japan!" Italy gasped standing up.
"Kesesese! Japan you look great!" Prussia burst out laughing, slamming his head on the table in front of him. Japan ignored him and took his seat. "Right. Now that we're all present we can-" Germany started. Unfortunately, he was interrupted by China standing up and going over to Japan. "What the hell did you do to your hair!?" He asked, pulling the younger nation to his feet.
"I just wanted a change!" Japan explained, trying to fend off China.
"Is it permanent?" He whispered. Japan blinked.
"So-sorry? I di-didn't quite ca-catch that!"
"IS IT PERMANENT!? TELL ME YOU DIDN'T USE BLEACH! I THOUGT I RAISED YOU BETTER THAN THIS! WHAT CAME OVER YOU JAPAN!" China shouted, catching Japan off guard. Russia put his hand on his ally's shoulder.
"Calm down. It's his decision what he wants to do with his hair. He's not a little kid!" China looked from Japan to Russia and back again, before sitting down next to Russia. Japan sat back down, a furious blush spreading across his cheeks. For the rest of the summit, he said nothing, only slightly sliding down his chair as time went on. "Alright. That's all. Meeting adjourned." Germany announced. He looked around trying to find Japan. He looked down to Veneziano and Romano who both shrugged. "Prussia? Did you see Japan leave?"
"No. Though I don't know how it's possible to miss him with that hair!" He burst out laughing again. Germany rolled his eyes at his brothers tactless comment. He checked under the table. "You can go home. I'll find him." Veneziano and Romano nodded and, after some hesitation from Veneziano, leave. "That means you too Prussia!"
"West I can't leave without you." Prussia muttered.
"Well wait in the car then. But I'm not leaving until I know Japan's OK!" The two of them stared at each other, before Prussia raised his hands in defeat and left. Germany opened the door to the bathroom down the hall and saw Japan leaning over one of the sinks, taking deep breaths. "Are you OK? Sorry about Prussia, what he said was unnecessary." Germany said, standing next to Japan.
"I made a mistake. I shouldn't have done this." Japan choked out.
"Ja, we all make them. Is it bleach?"
"No, I didn't want to risk going that far. Which is why it's more like America's colour..."
"Permanent?" Japan shook his head and Germany sighed with relief.
"Well when you get home, wash it all out. Ja?" Japan nodded again. Germany guided his friend out of the bathroom, down the hall and out into the street. Germany looked around for his car and frowned. "Germany-san?"
"Dammit! Prussia left. I'll see you tomorrow Japan." He started walk off, but Japan stopped him.
"I can drive you if you want?"
"Danke!" The two got into Japan's car and drove to Germany's. Before he got out, he turned to Japan.
"Don't take what Prussia said to heart. Sit under the shower. Prussia, Italy and I will come and get you and we'll go out to eat ja?"
"Hai. Thank you, Germany-san." Germany got out and Japan watched him go inside. Once the door was shut he groaned and hit his head on the steering wheel.

The next day, Japan stared at himself in his mirror and sighed. He'd spent most of last night under the shower rubbing the dye out of his hair. Luckily, it had come out easily and his hair was back to it's normal black. "How I managed to get it all out is a mystery!" He muttered to himself. He remembered that Germany was coming at some point. He changed into a jumper and jeans and sat stroking Pochi. After a couple of minutes, a knock came from the door. He answered it and was greeted by Italy giving him a hug. "Japan! Thank goodness! Your hair is back to normal! I was worried you'd have to stay like that forever!" He rambled. Japan awkwardly patted his friends back. "Ple-Please! Italy-kun! You're suffocating me!" Japan choked. Germany moved forward and pulled the small Italian off Japan. "Calm down. Ahem! Prussia?!" He nudged his brother.
"Oh, right. Ja, I'm sorry for what I said yesterday. It was out of order. Am I forgiven?" He sounded sincere, so Japan nodded.
"Of course you are Prussia-san." Italy smiled, and lead the way to the restaurant.