"Don't worry about it."
Gojo's smile was breezy, confident.
"I'll figure something out when the time comes. Trust me."
Puck didn't press the issue. Whether Gojo could get back into the Forbidden Library wasn't really his problem anyway.
They were still talking when Betty returned, a book tucked under her arm.
"You may only read it here. The book does not leave this room."
"And Betty does not want to see you again after this."
Her expression was ice as she held it out.
"Understood. I won't take the book."
Gojo's tone was warm, agreeable. The part about never wanting to see him again went in one ear and out the other.
Whether she saw him again wasn't up to her.
"Hmph."
She tossed the book at him rather than hand it over, as if closing even that small distance was beneath her.
He didn't mind. Catching it, he dropped cross-legged onto the floor and started reading.
True to his request, the contents covered Yin Attribute magic.
As he flipped through, a clearer picture of this world's magic system took shape.
Casting spells hinged on two factors.
The first was Mana manipulation, which came down to the quality of one's Gate. A Gate served as the channel linking the body to atmospheric Mana, responsible for absorbing, storing, and outputting magical energy. Its size and stability were fixed at birth, determining absorption rate, storage capacity, and output efficiency.
If the specs were too low, a person couldn't even meet the Mana demands of basic spells. Nothing more to discuss.
Subaru was a perfect example. Precise control was beyond him. If he couldn't even manage Shamak, the most rudimentary spell there was, higher-level magic was out of the question.
The second factor was raw Mana reserves.
Greater spells demanded greater power. If a high-level spell required sixty units of Mana and your total capacity was fifty, you'd never cast it on your own. Not without some miracle.
Becoming a mage on the level of Roswaal wasn't a matter of effort. It was talent.
In that respect, the system mirrored Jujutsu Sorcerers almost exactly.
Gojo turned another page and found his thoughts drifting toward a deeper question: what separated Mana from Cursed Energy at a fundamental level?
Cursed Energy was extracted from human emotion.
Mana permeated the atmosphere itself.
One was manufactured by the human condition. The other was natural, ambient.
Yet the Yin Attribute Mana he'd been working with bore a striking resemblance to Cursed Energy in both composition and behavior.
Using Cursed Energy to cast magic, though? That didn't work at all.
So it comes down to those subtle differences.
From what the book described, advanced Yin Attribute spells gained offensive capability but still leaned heavily toward support and debuff applications. Even pushed to their absolute ceiling, they couldn't rival Cursed Energy in raw destructive potential.
Used in combination, though, the two could complement each other nicely.
The book contained several spells in total. Gojo studied each one, committed them to memory, then stood, dusted off his pants, and walked over to where Betty was playing with Puck.
"No patience at all, human."
"No, calling you human is too generous. Monkey suits you better."
She was holding Puck aloft, mid-game, and the sight of Gojo standing up so soon earned him an immediate volley of scorn.
"Monkeys are cute too, aren't they?"
"Thanks for the book. I've finished it."
He set it on the table. "See you tomorrow, then."
"Nobody said anything about tomorrow!"
"Betty forbids you from coming back!"
He was already walking away, one hand raised in a lazy wave over his shoulder.
"Brother!"
"Don't let that awful person in here again."
Betty watched him disappear through the library door and turned to Puck, lips pursed in a pout.
"Heh, got it."
Puck scratched the back of his head, sheepish. He didn't have much room to argue. Today's whole mess had started because he'd talked big about supervising Subaru and then let things spiral out of control.
The door deposited Gojo not back at Subaru's room but in a first-floor corridor off the main hall.
Through the window, he spotted Felt sitting on the front steps of the mansion, chin in her hands, staring at nothing.
"What's the matter? Haven't seen you all day."
He stepped outside and dropped down beside her.
"Nothing. Bored, that's all."
She propped her face on her palm, gaze fixed on the distant scenery.
"Missing Old Man Rom?"
Her head didn't turn. "No."
"I'm not a little kid. Why would I..."
"Really?"
Gojo reached over and turned her face toward him, studying her expression.
She swatted at his hand, struggling to free herself. But she had about as much chance of overpowering him as a kitten wrestling a wolf, and she gave up with a deflated sigh.
"Missing family isn't something to be embarrassed about."
"I'm sure Old Man Rom misses you too."
He let go, stretching out his legs.
"I said I don't."
Stubborn pride kept her chin raised, refusing to admit it.
"I'm bored here. That's all it is."
"And how much longer are we staying, anyway?"
Gojo rubbed his chin. "A while longer, probably. There are a few things here that interest me."
He glanced sideways at her. "You should take advantage of it. Relax a little. Life before this wasn't exactly easy, was it? Once I've sorted out what I need to, we can head back."
"Or we could bring Old Man Rom here to live with us."
"Bring him here? To live together?"
Confusion clouded her face.
"Don't overthink it. For now, enjoy the downtime. I'll explain when the time is right, but not yet."
"See, this is exactly your problem! If you're not going to tell me, then don't dangle it in front of me like that!"