AN: This occurs before the first visit to Ehmead Hill, so the party's just escaped the knights in Halure after they learned about Overlimits.
There were no inns between Halure and Ehmead Hill, of course, so when everyone else was getting tired from their quick escape, Yuri decided they should make camp. There wasn't much of note along the road, but they did manage to settle comfortably enough in a grove of trees that stood a few yards from the dirt path.
Since Estelle practically jumped at the chance to look for water with Repede, Yuri started making some sandwiches. Rita sat on a rock reading, while Karol stood unusually alert-and jumped at the chance to fight a monster that wandered too close, something that Yuri found interesting even if Rita scoffed that the only reason was that the monster was hideously weak.
It took barely a few swings for Karol to defeat it, but as he turned back to Yuri, there was a dejected look on his face, so he set down the ingredients and asked, "What's up, Captain?"
With a sigh, Karol slumped down heavily to sulk. "It's just...I can't get it to work like you guys do!"
"What is it?"
"That super secret technique!" When that didn't go through, he clarified, "Overlimit! I just can't do it..."
Yuri could only shrug nonchalantly. "Estelle hasn't mastered it yet, either." That made Karol shake his head and stand up again, agitated.
"But I've got plenty of battle spirit! Just like you, Yuri!" When Rita snorted, he stomped his feet. "It's true!"
"You just need more practice," he answered. Yuri wasn't worried-Karol was pretty young, and Estelle wasn't used to fighting real battles yet, but they'd get the hang of it if they kept their minds to it. "Maybe you need to have more fun in a battle. You know, like me and the genius mage, here."
Moodily, Karol muttered, "Rita doesn't battle. She just bullies." And then he jumped when Rita shut her book with a snap and stood up sharply, having grown sick of listening to them.
"Shut up, runt! The difference is that I'm a genius and you're an idiot! That's why I can do it and you can't." Before he could stop sputtering and start protesting, she'd whirled on Yuri next. "And you-stop going on about that 'battle spirit' garbage!"
"You're a real idiot if you think that's what generates an Overlimit."
Yuri sighed, raised an eyebrow, and prompted, "So what does make it happen?"
"Simple. Whenever you process the aer for your artes or get hit by an arte, a certain percentage of aer that's only been half-processed builds up. It's stable at first, until you have enough aggregating, and then you're able to utilize it-because it's already been partially processed, you can use artes almost instantly. The aggregated aer helps protect you from attacks, too. Oh," she paused for just a moment in her quick lecture, "if you build up any more beyond that, it gets too unstable and reacts on its own. That's why you're out of luck if you don't use the Overlimit at the right time. Got it?" Her responses were pretty much blank stares and noncommittal responses, so Rita growled, massaged her temples a second, and amended, "Okay! You build up extra aer by fighting and use it when you have enough! Do you have it now?"
"All right, all right!" Karol waved his hands quickly, more to get Rita to back off than to indicate that he understood-which he didn't, really. At least, he didn't think it sounded any different from Yuri's battle spirit explanation. But Rita didn't look convinced, so he hastily made an excuse about practicing more and dashed off.
"Idiot," Rita grumbled, and Yuri only sighed. He hadn't understood it at all, either.
Later, when Repede returned with a bucket of water but Estelle stayed apart from the campsite, Yuri went to meet her-and found her standing still, arms spread, breathing deeply. Was she…meditating? "...What're you doing there, Estelle?"
"Oh, Yuri!" Estelle opened her eyes and turned her head to smile at him, but otherwise didn't change her posture. "I heard that Rita explained how to use an Overlimit, so I'm trying it now." Facing forward again, she closed her eyes, and Yuri was left uncertain.
"Exactly what are you trying out here?"
"Well, Karol said I had to build up lots of air. So I thought breathing would help!" With that, she took as big a breath as she could, then exhaled slowly. She certainly felt lots of air build up in her lungs and it rather refreshed her, but it never did help her with learning Overlimit.