"Right this way, then." And they show him to someone suffering mild chakra exhaustion, and set up the same monitoring.

"I'm a bit curious what my own detection will make of chakra exhaustion, actually, if you don't think it'll interfere - I have two of those," he reminds Tobirama.

"It seems likely to be interesting," Tobirama says.

"We don't think it'll interfere," is the medic's opinion.

"With your permission?" he asks the patient.

The patient grants permission.

The detection spell makes his eyes glow for a moment; the healing is just the same as last time.

Status: the patient is suffering from mild hypothermia for no apparent reason. It seems more like his body's ability to generate heat is shutting down. He's lethargic, likely depressed.

Healing: it very briefly relieves symptoms, which reoccur within a few seconds, with an apparently uncomfortable backlash. The patient isn't harmed, but the underlying problem isn't cured.

He apologizes for the backlash and thanks the patient for his help. To the medics: "That's interesting - it seems to be some kind of ongoing effect, then. If I had to heal it myself I'd try a treatment for ability damage next, possibly something to boost constitution."

"Do you have something for that today?"

"I have a Lesser Restoration; it won't fix it entirely unless it counts as an ongoing magical effect, but it might help a bit even if not. And I do have a few potions that boost constitution, but those are irreplaceable, I'd rather wait and cast that spell myself than use one on a test."

"We can wait for tomorrow. I'm not sure it'd count as an ongoing magical effect - being out of chakra is more a lack of an ongoing magical effect."

He nods. "Even if the constitution-boosting spell does work it's not a very good solution; it'll last half an hour at most. In my world you could get a magical item for an ongoing effect, but I don't have one like that with me. But it's worth trying, anyway."

"What does constitution do, the way you're using it?"

"It's how healthy you are, broadly - how much damage you can take and how well you heal, how well you resist diseases and poisons and hot and cold environments, how long it takes you to get tired when you push yourself, that sort of thing. The other physical abilities are strength and dexterity."

"Those don't sound at all like the way we'd describe things - chakra capacity increases with both mental and physical might, but I'd expect something temporary that modifies those to actually not alleviate the problem and to make it worse when it wears off."

He nods. "I probably shouldn't try anything else, then, besides seeing if I can get a spell specifically for chakra exhaustion."

"You'd have to be careful not to overshoot; having too much chakra's rare, but it can cause problems, too."

"I wouldn't expect to have that problem; my magic is generally good at that kind of thing. But I'll keep it in mind."

"It's worth trying, at least."

He nods.

"How much should I prioritize that?" he asks Tobirama.

"Deaths from chakra exhaustion are relatively rare, and usually occur in the field far from medical treatment anyways - it's fairly obvious if you're running low, and your mental ability to actually use chakra also goes down as you run out."

"I'll save it for when I have some spare spell slots, then."

"It would be interesting to know if the systems interact correctly, yes."

"And if I can get a spell for it it should be possible to make protective magical items, too, once we find my world again. Anyway, what's next?"

"I think you might need a more thorough explanation of how chakra works, before any spell development."

"Next I'd like to try a case of blindness due to overuse of a specific bloodline." Fortunately, he's managed to contact the only other person among the Uchiha suffering from Mangekyou-related blindness without alerting Madara (she'd agreed about the importance of not getting anyone's hopes up.)