In the end, the decision is easy.
Passing up a chance to have a beautiful woman hang on to your every word, demonstrate the breadth and depth of your experience, and be rewarded in the process?
"Of course I'll teach you, Ruri," you say, kissing her smile away. Terribly sappy, but sometimes dignity must be sacrificed in the name of manipulation. "You've already proven that you're a very fast learner, after all."
You press her off you gently, and sit up.
"I can't start immediately; there are a few things I need to do over the coming days, but starting next week we should be able to pick out a convenient schedule for the both of us."
A convenient schedule for you is, of course, pretty much whenever, because once you're finished with Nabi you're not exactly doing anything else. You have vague plans for self-improvement; mostly setting up another ritual to continue studying your soul, and learning a lot more math and physics. Apart from that, however, your time is looking fairly empty. You can't work all day every day, you'd go insane.
Ruri doesn't need to know that, though. As far as she's concerned, you are offering her a great privilege. And you are. She should be honoured to receive your instruction.
"Oh? What are you doing?"
"Nothing you should worry your pretty little head about," you say, and smirk at her infuriated expression. "Really, I'm serious. Just some research for Lord Azazel."
The best sort of lie, after all, is the one that is entirely true.
"Secret Faction business," Ruri says, sighing slightly, "yeah, I get it."
"Well, that's one less element of supernatural etiquette I'll have to teach you."
"Hey! I'm not that dumb!"
"What?" you ask. The expression on your face would make innocence look like it had just been caught in flagrante delicto by comparison. "As your teacher, I wouldn't be doing my job if I didn't find out what my adorable student needed to learn."
Ruri pokes you in the side. "Don't be mean."
You roll over her abruptly, hands pressing into the sheets just above her shoulders on either side of her head. Your hips settle above hers, and you lean down in a mirror of her earlier position.
"Are you saying you don't like it?" you ask, breath whispering across her skin. She doesn't blush – but she doesn't deny it either. "I thought not."
You lift yourself off her, not bothering to hide the satisfaction in your smile.
"I have to go soon," you say, "and you probably have to get to work, right?"
The dawning horror on her face is hilarious. "Oh no. What's the time?"
There's a clock on the bedside table next to you. It says it's seven o'clock. When you repeat that to Ruri, she almost trips off the edge of the bed as the sheets threaten to tangle around her in her haste to get up. You're quite happy to sit back as she rushes around; hate to see them go and love to watch them leave, indeed.
"Sorry I've got to go I really enjoyed this I'll see you later bye!"
Her delivery is fast enough to make a machine-gun jealous, and the speed at which she runs out the door would make a bullet feel similarly.
Idly, you wonder if you should tell her she left her clothes behind.
Eh, she's a kitsune. She has illusions. It'll be fine.
And speaking of kitsune, you've got another to meet later today. Ideally, you want to get the capture done, not just the battle-plan, and that means you have your own preparations to make. You weren't capable of it back in Kuoh—too little raw power and never enough need until it was too late—but between the ambience of Kyoto's leylines and your own, more vibrant soul, you think you might be able to construct a quick ritual that will help in a fight like the one you're heading into.
(For all you know, Nabi has some clever idea based on situational knowledge you aren't aware of that will mean there won't be a fight after all. You hope not. You've wanted to kill something since you let Freed Sellzen go, but you'll take beating some uppity Shinto priest with a Gear he doesn't deserve to a pulp if you have to).
You decide on Ava's Demon. Invented, unsurprisingly, by a woman called Ava—apparently in response to the actions of a Devil—it fortifies the soul against spiritual possession, and to a lesser degree spiritual damage. At least for a time. The Shinto are big fans of using spirits, so it'll surely come in handy.
Luckily, you have the necessary supplies in your ritual kit—though you are running low on silver dust; probably want to do something about that at some stage—so by the time Nabi arrives, you've just finished casting it. You can see her out your window on the street below, and when she glances up directly at your apartment, you wave. She looks unimpressed.
How unfortunate.
You dress yourself in something loose and easy to move in, and lock up the apartment as you leave. Soon enough you're on the street, leaning against a lamppost and studying Nabi; she's wearing the same suit as she was in the morning, as freshly-pressed now as it was then.
"So," you say, "what's the plan? I don't know anything about where this guy is, and neither of us know what his Gear does – but like I said before, you don't strike me as the sort of person who decides to kill on a whim."
"The priest lives at the temple, which is surrounded on three sides by apartments, and a small park on the fourth. He is the only one there at night. Inevitably it will be protected by wards as well as whatever spirits he's summoned to help handle the upkeep of the shrine. I was intending for you to disable the wards during the witching hour so that I could sneak in past the spirits and take care of the priest while it's still dark. Can you do that?"
"Depending on how extensive they are, maybe," you demur, "and I can't guarantee any alarms won't go off in the process. Are you sure—human or not—that you really want to tangle with an unknown Sacred Gear wielder alone?"
"Do you have another suggestion?"