Isabelle stood back up, her butt jiggling as she began patting it with her hand in search of what she sat on. When she poked you and made you curtly yelp, she let out a gasp of surprise. "Oh my gosh! I sat on a human! I'm so sorry, sir! ...Hang on, what are you doing at my desk?"
"W-wandered in and needed a rest," you white-lied, squirming against her panty fabric. "H-hey, uh, your butt's comfy and all, but can you lift me off?"
"Okay, and thank you!" You can hear her delight from the praise in the tone of her voice as she peels you off her underwear, bringing you around to her face... letting you also see how her green gingham top is being stretched out by her furry yellow bosom. "Aw, you look pretty cute, too!"
"Aw, t-thanks... Uh, m-my name's Anon, what's yours?" You asked, trying not to look like you already knew the answer.
"Oh! Uh, allow me to introduce myself!" She set you down on her desk, bowing and making her boobs squish between her arms in the process. "I'm Isabelle, mayor of Giantopia! ...Well, acting mayor. I'm really just the secretary, but the town hasn't had a mayor for a while now."

"Acting mayor? Geez, that... must be rough."
"I-it's not so bad!" she said in the tone of someone who was running on fumes, "Just going around town, checking in on everyone, hearing everyone's complaints about what's going on in town, struggling to collect funds, dealing with the summer heat... woof." She tugged on her shirt, giving you a spellbinding glimpse of her sweat-soaked bra. "...A-alright, m-maybe it is a bit rough. B-but I can handle it! I've gone this far on two hours of sleep last night, I can keep going!"
"S-sounds to me like you really need a rest," you noted grimly, as a thought comes to mind... "Say... perhaps I could become the new mayor?" That was what happened in New Leaf, after all, albeit there with a bit of a misunderstanding.
"You, as a mayor?" Isabelle asked in surprise, picking you back up. "I... well, much though folks in town love humans, one hasn't been a mayor in decades—even before I arrived here!" She glanced over at a wall of mostly-unfamiliar faces (Tortimer you expected, but Rover was a mayor of this town?!), and sure enough, there was one of a human, the picture very zoomed in and the man himself leaning on a photographed mug. "But, uh, I think we could make it work."
"That's good to hear." You gazed down at Isabelle's cleavage, blushing deeply like before. "Um, can you set me down there? I could help deal with your sweat."

"Y-you want to be my sweat rag?" she asks in surprise. "Y-you don't need to do that, mayor! I'll be fine!"
"No, no, I insist, especially since you've clearly had a rough day... Uh, u-unless climbing around there is a faux-pas with a giantess like you."
"Oh, don't worry about that!" she says as she drops you into her rack, continuing to speak as you clambered around, soaking up remarkably cool-feeling sweat from her fur. "It's more than okay for you to climb around on me, most of the large residents here do that with the humans of Giantopia. I mean, Tom Nook lets them stay in his cock while he makes them a house... Oh my gosh, I forgot!" Isabelle began shaking in worry, leading you to cling to her nipple to avoid bouncing about. "Y-you're going to need a home address if you're to be the mayor here! ...O-oh, sorry. That tickles."
"I-I'm sure that'd be fine," you noted, continuing to massage her nipple with how much she enjoyed it. "I mean, it can't be that hard to build a house for someone my size, can it?"
"It shouldn't be. Mr. Nook makes them so that they can survive getting sat on by an elephant, and Opal in particular's a heavy pachyderm... Oh! You could always live at her house!" she realized. "Or at mine, it's not too far across town from here... Ooh, or maybe we could have me be your house?"
"You? ...A-as in, your clothes? O-or, like, your insides?"
"Either/or would work," Isabelle said, looking down... and getting a grin on her face from how you must have looked. "I can tell you like the idea, Mayor Anon! Want to be up nice and snug with my butt again, don't you?"
"M-maybe. Or elsewhere."
"Well, we can always workshop it. You know, there's lots of humans in this town who live on or in the bodies of its animals, although its... not really an official thing."
"Maybe with me living on you, it can become official."

Isabelle seemed flustered at the thought of that, and her boobs bounced a few more times as she got seated. "M-maybe so! T-though, that depends on if it's what you want to do."
Good point. How would you handle getting an address in this town?