Umi flopped backwards onto the bed with a dissatisfied huff and swore at the ceiling, her arms aching thoroughly from the several falls she’d taken in their training session. Tarta, didn't cackle at her - the expected response, given that she’d caused most of the falls, introducing Umi to fighting with a curved sword - just stared.
“What did you say?” she asked, voice quivering.
“…Something rude?” Umi had no actual memory what she’d come out with. “’Shit that hurts’, probably. Why?”
Tarta snorted. “I don’t think the translation spell is, uh, working right on whatever you’re saying. Unless you’re really saying ‘oh stony ground I hurt’?”
“…No?” Umi blinked, and then started to snicker. “Why would - no, stony ground wasn’t involved, it really translated like that?”
“Quick, say something else impolite, I want to know if it’s just that one!” Tarta plopped down on the bed beside her, grinning. “Or if there are others - and you’ll have to tell me what you actually mean, too. Literally, that is.”
Umi went to push herself up on her elbows, then thought better of it after a few painful moments, and stayed flopped on her side watching Tatra. “Why? Just so you know what I’m actually saying?”
Grinning more broadly, Tarta waved a hand. “No, so I can swear in public so you understand what I mean but no one else does.”
At that, Umi cracked up, flopping onto her back and laughing hard enough her ribs hurt.
It was a little unfortunate that half the official meetings they were both going to at that point were about the revival of Autozam, which involved rather a lot of discussion of stony ground - as they were trying to decide on test areas for the revitalisation techniques which were being developed. By the third day of looking at each other and starting to snicker in the middle of some completely innocuous discussion, Fuu pulled Umi to one side and asked what she and Tarta were laughing about so much.
Fuu was the one who was curious enough to enlist Ferio to find out if the ‘translations’ were the same for a Cephiran listener, which, as it turned out, they were not.
(It turned out that the different lands all had their own languages, which were all translated to the girls as ‘Japanese’, and a common language between them which Tarta would use to talk to Ferio - only it was similar enough to Cephiran that the Cephirans just used their own tongue, which was useful as none of them would have been learning an international language for all the years of isolation, making the invasion even harder to deal with. It had been bad enough as it was, without being unable to talk to each other.)
And then there were four of them trying not to laugh at the most innocent of phrases… which lead swiftly to Clef, having tried to ignore the snickering as long as he could, pulling Ferio to one side for an explanation.
He had to call a pause in the next meeting before he too started laughing inappropriately.
Umi clapped Tarta’s hand at that - and got glared at, but it was worth it for the way Clef's lip started twitching up every time either of them dropped one of the phrases into conversation.
Tarta nudged Umi's shoulder during the next meeting, leaning in close to whisper in her ear. "Diplomacy by shared jokes?"
"I think it's a great plan!" Umi grinned at her. "I don't know who we should include next, though."
"Not Tatra," Tarta said, snickering. "She'll tell me off even if she's amused. …Geo Metro looks like he could do with laughing more often, do you think he'd appreciate a way to say what he really feels without upsetting anyone?"
"One way to find out!" Umi said, brightly, and giggled again as Clef shot a look at them across the room. She was sure they could find a way to chat quietly with Geo in the evening.
Everyone needed to blow off steam sometimes, after all.