Katsuko looked him in the eye, steeling herself. “And what happens when the seal finally does disintegrate?”

“I don’t know,” Kakashi said honestly. “Nothing good, probably.” He flipped through the cloth-bound book’s yellowed pages, stopping at an entry near the back and turning it to show Katsuko. "These are chakra seals, but I don't know if any of them are strong enough to hold in the amount you have. I could try rebuilding the seal, but the basic structure is flawed. It might buy you time, but it wouldn't hold forever."

Katsuko stared at the spidery, almost illegible scrawl next to the drawings of strange seals, gaze distant and contemplative. “Kaminari and her husband are still out there,” she said, quietly. “Whatever time you can get me will have to be enough.”

“You said something about research data, last week,” Ryouma prompted, squeezing her shoulder. “If you had copies of Kaminari’s notes, Kakashi, could you reverse-engineer a fix?”

“Maybe, but the same seal would have all the same problems.” Kakashi hesitated. "There's another choice, but it's more risky. We could make a new seal, using this as a base. I think it's possible to make one that would last." He rifled through the books and scrolls in his lap, spreading them out and pointing to various drawings. "If I filled in the dead space with something functional—a vent to stop your chakra building up, and a stop-gap to make sure you can't overload—I think Kaori Shin's temple-gate seal would bastardize for that..." He glanced back up. "It wouldn't shrink your coils, but it might give you your control back. If I could make it work."

“Oh,” Katsuko breathed. “Oh.” She swallowed, throat working as she stared down at the drawings. Something very like hope entered her eyes as she looked up at Kakashi, faintly stunned. “You do. You actually think you can do this.”

His eye creased a little at the corners in a definite smile, Sharingan gleaming dully in the light from the windows. “If you’re willing to take the shot.”

Katsuko laughed, a little wildly, turning to Ryouma with a wide grin. “I can honestly say I’m jealous of you right now, Tousaki. Damn, he’s good.” She looked at Kakashi, eyes bright. “Let’s do this.”