Warnings for extreme violence and a lot of blood. The Koreas' escape method is a tad drastic, but they are in too much of a hurry to try many other ways and it's a lot less of a problem than it would be for a human.
Japan didn't realise he'd fallen asleep until he was jolted awake by a clattering and a yelp from the kitchen. Korea! What was the little pest doing now? He checked automatically to make sure the keys to the door and to his brother's shackles were still in his pocket. Of course they were. Good.
And what on earth was that smell? Meat? ... Blood.
Japan sent paperwork flying in his rush to the kitchen, picking up the cane on his way just in case, and gasped with disgusted horror as he saw the mess on the floor. Korea was leaning against the table, breathing heavily, his chains lying loose on the floor before him. Japan realised he'd forgotten to lock the kitchen cupboards. He'd checked the doors and windows, but Korea had been so good recently that Japan had become lax with locking away the sharp things. Several broken wooden skewers were scattered around; evidently Korea had tried and failed to pick the lock, and resorted to more extreme measures. The meat cleaver was lying next to the chain, its blade scarlet. Korea was shaking, whimpering, clutching his own severed left foot, holding it to the stump and watching the skin and tendons heal back together. Judging by the flood of red around him, he'd done the right foot the same way.
"What the hell?" Japan shouted, staring, half angry and half horrified. "What do you think you are doing?"
Korea looked up, and his expression of pain was replaced by a wicked smile. "Leaving, brother dear."
"Wh-what?" Japan raised the cane to protect himself, backing away slightly.
Korea stood up, slowly, carefully, wobbling on his newly-healed legs, giggling eerily. "I was hoping not to wake you, but I was in a hurry. Doesn't matter. I'm going home and you can't stop me, you piece of shit."
His voice was much higher-pitched than usual, feminine in fact, and made him sound like a whiny child; it would have been comical in any other situation, but as it was, Japan was acutely aware of how Korea was much bigger than him, and he wasn't entirely sure how strong the boy was.
"L-look, was this really necessary?" Japan stuttered. "Now now, you're not in trouble, I can see you're upset, just calm down and we'll talk about this over some tea-"
"Necessary?" spat Korea. "Probably not, but it got the chains off me fast enough, didn't it?" He left footprints of blood on the wooden floor as he loomed over his frightened captor.
Japan took another step back. What had got into the boy? Maybe there was a rebellion going on back in Korea, but if so, why hadn't anyone told him about it? "Kor- Yong-Soo! I don't know what's happening, but I'm sorry-"
"NO YOU AREN'T!" Korea lifted Japan off the floor and shook him like a ragdoll. Stronger than Japan had thought, then. Annexed territories tended to be weakened at least a little by their overthrowing, but as with humans, sheer anger could lend them strength. Japan's breath was knocked out as Korea slammed him against the wall. "I hate you! I hate you so much!" Korea screamed, hurling Japan bodily to the floor. Japan tried to scramble away, and Korea kicked him in the side, backing him into a corner. "We rotted here for thirty years because of you! Thirty years! Thirty years lonely and scared and knowing what you're doing to our people!"
"Well, that's more than I know," Japan muttered deliriously, and was rewarded by another kick. Korea picked up the fallen cane and rammed the end into Japan's throat, making him cough.
"And not just us, I know what you did to China!"
"What? I didn't do anything to him!"
"LIAR!" The cane swung down on his face, again and again. Japan curled up to protect his head, and his attacker started stamping on his ribs. He gasped as he felt one snap, then another. "Liar! Liar! You raped him and you're a filthy LIAR!"
Japan's eyes widened as the words brought back hints of memories. China bloodied and half-dead, China clutching his pipe like a protective talisman, China screaming in his sleep ... Had Japan ... he hadn't, had he? He couldn't remember. He didn't think he had.
Korea stopped kicking him and stood back, breathing heavily. Japan dared to uncurl slightly, and saw the gleam of metal.
"What are you- no, no, don't you dare-"
The cleaver swung down. Japan screamed as it cut into his arm. Tears of rage streamed down Korea's face, and the blade met Japan's flesh again and again. Japan tried to grab it and wrestle it away, succeeding only in cutting his hands. Japan started to feel sick, blood loss combining with the effects of his head injuries. He knew he should try to fight, but he couldn't get up. Was this how China felt? he thought deliriously, and couldn't remember why.
Maybe it was okay that he couldn't fight. If Korea was right, maybe he deserved this.
As he passed out, Japan's blurring vision caught sight of the golden glint in Korea's eyes, and the down-turned curl. His lost sister had had the same eyes.
"... Balhae?"
Korea gave him one last kick to the head, and Japan mercifully succumbed to unconsciousness.
Korea stood back and examined the unconscious man. Already his wounds were starting to close up. That was bad. Better make sure he wouldn't wake for a while. It took a lot of hacking and swearing, but soon Japan's head rolled across the floor. Korea wrinkled her nose and went through his pockets; here were the door keys. Perfect. She'd been prepared to break the door, but now she didn't have to attract attention. She quickly stripped, wrinkling her nose as she was forced to confront her body - all lanky muscle and wiry hair, wrong, ugly. No matter, it served its purpose. She wiped the blood off with water from the sink and ran to fetch fresh clothes.
Most of Japan's shoes were too small for her, and she didn't know where he'd put their old ones; they hadn't been allowed outside in years, so they hadn't needed shoes other than cheap, thin slippers. Finally she found an old pair of wooden sandals; her heels hung off the backs, but they were better than nothing. In the closet she found an old, battered hat; she put it on, and tucked their distinctive curl under it, trying to restyle her hair a little with her fingers. She stole Japan's coat, and stuffed the pockets with as much food as she could fit in. She was pleased to find the coat hid her lack of a feminine figure, though she could do nothing about her awkward height.
She locked the front door behind them and, just to make Japan's life a little more difficult, threw the keys down the nearest drain.
The rain was falling heavily by now, so few people were on the streets. She didn't run. She held her head high and walked as if she owned the town, despite her battered body and ill-fitting clothes. Nobody connected the confidently strutting fox-eyed figure with the local semi-recluse's troublemaking servant boy.
Sis? Was I asleep? What's going on?
Under her breath, she replied "We're free, brother dear. We're free."
North Korea turned their face up to the rain, and laughed.
