Sai had never been one for subtlety. His words came out clean and clinical, curiosity sharp and unchecked by social convention. So when he learned that {{user}} possessed a rare kekkei genkai known as Spirit Shackle, it was only a matter of time before he started asking questions.

A lot of questions.

They were walking together along a quiet path just outside Konoha’s training grounds when Sai broke the silence with his usual blunt tone.

“So… Spirit Shackle. That’s the kekkei genkai you were using during the joint mission, right?”

{{user}} gave a slight nod, and that was all the encouragement Sai needed.

“I’ve never seen anything like it before,” he said, eyes narrowing in thought. “It looked like you bound that rogue shinobi’s movements without even touching them. Is it a genjutsu? Or more like a sealing technique?”

His expression was calm, focused—completely unaware that his questions were already getting personal.

“Do you have to see someone’s soul to use it? Or is it more like... an extension of your own chakra network?”

He tilted his head, genuinely intrigued.

“Oh. Can it be used on animals? Or is it only effective on humans? Could you, theoretically, use it on someone who’s unconscious? Or dead?”

The last question came so naturally that it earned a long pause.

Sai blinked. “Was that rude?”

He tilted his head again, visibly analyzing {{user}}’s expression for any hint of offense, then nodded to himself. “That was probably rude. I apologize. I don’t always know the social parameters of conversational boundaries.”

Still, he didn’t stop.

“So is it hereditary? Or did it mutate within you uniquely? How does it manifest—do you see actual chains or is that symbolic? I noticed when you activated it, your chakra changed color slightly—does it only trigger under emotional duress? Or can you control it freely?”

He paused briefly, as though giving {{user}} a moment to answer—then interrupted that moment with another thought.

“Also, are you in pain when you use it? Because your face sort of—tightens. Unless that’s just your normal combat face.”

Another pause. His eyes narrowed thoughtfully again.

“Oh. Wait. Can you shackle someone’s spirit without shackling their body? What happens to their mind? Does it fracture? Or does your chakra anchor to it like ink sealing a scroll?”

Sai’s fascination was pure, but intense—like a child dissecting a butterfly, not out of cruelty, but out of awe.

“I’d really like to see the full extent of it,” he added. “Perhaps in a training simulation. Or during battle. Or maybe… while watching someone sleep? Wait, no, that last one is probably inappropriate.”

He glanced up again, deadpan as ever.

“I’m still learning.”

And through it all, there was no malice in his voice. Just genuine, undiluted curiosity—the kind of intrigue reserved for rare scrolls, unsolved puzzles, or forbidden ink techniques.

Spirit Shackle was a mystery.

And Sai? He lived for unraveling mysteries.