“Give me a minute,” Kakashi said, dropping the kit in trade for another scroll. He pointed at that inner ring. “This bit doesn’t mean anything; it’s just dead space. Half a good luck charm that doesn’t actually do anything, but it’s holding up these two poles—” he pointed to two spiked structures bleeding towards Katsuko’s right hipbone, “—and I think they’re tied into forcing her coils continually open, like jamming a stent into an artery. But that doesn’t explain why she doesn’t run out of chakra...” He looked at Katsuko. “Have you ever had a chakra crash?”

Pale but stone-faced, Katsuko shook her head. “I haven’t needed soldier pills since the seal.”

“What’s the biggest jutsu you can control?”

Katsuko thought for a moment. “Fire and wind combined in a storm about a mile wide.”

Ryouma whistled softly.

If he tried that, Kakashi suspected he wouldn’t move for two days. “And how do you feel after? Tired? Better? More normal?”

Katsuko looked away. "Angrier. Hungrier. Like it's not enough. Like I can do more, if I just let go.”

Until she burned herself up completely.

“You’d probably blow a crater in the earth half the size of Konoha if you tried that,” Kakashi said bluntly.

Ryouma’s hands wrapped around Katsuko’s shoulders, as if he could rub away the unhappy shiver in both their scents. The kitchen air was starting to smell a little more crispy than it was supposed to, but Ryouma made no sign to rise. He did take his hands away from Katsuko long enough to make a pale shadow clone and send it in his place. Katsuko’s mouth twitched.

Kakashi pulled two books into his lap, including the one from his weapons chest—the only one he’d ever bothered to take from the abandoned Hatake estate—and one of the scrolls, spreading them open as he talked.

“I think what’s happening is that the luck charm isn’t the only dead piece, and a rest of this is just stitched together from bits of other seals. You said it was a prototype; I don’t think it was meant to last this long. It hasn’t lasted.” His fingers brushed over three different spokes, where the red ink was almost rust-coloured, frayed at the edges. “These pieces are disintegrating, and it was never stable to start with. If I had to guess, the only reason it’s still functional is because your chakra pathways were growing when it was put in, and they adapted. It’s your control that’s keeping it whole.”