Oh my.

What is she reacting to?

Her expressions are perfect - great to see what's going through her mind. The tags are also a nice touch and help to further build the story here. Kudos once again.

You guys must be new here. It's a colored remake of this of a gif the Admin made a while ago.

She's reacting to the lingerie she's wearing (hint: she likes what she sees).

I'm hardly new here, though it's been some time since I looked at the previous animation. I enjoy it when a piece gets revisited like this.

"It fits and..."

"Wow, I look kind of sexy...."

"I wonder if Master will get hard if he sees me...

"Oh god!...."

To be honest, the arms need a bit of animation, she looks stuck in that one position as she realizes she likes being showy

She's trepidatious and self-conscious, at first, at being so exposed and on display, but then she realizes how beautiful and sexy she looks and how the skimpy bra and panty set compliments her figure and its voluptuous proportions, and she falls in love with the ensemble and how they look on her, practicality gushing with giddy girlishness at how irresistibly temptatious she looks wearing them and can't wait to take them off for the right suitor -- or for that suitor to liberate them of her with unbridled lust as they ravage her femininity with abandon!!

Q&A @The_Admin:

I like the earlier commenter's suggestion (penultimate to this one of mine) for animation of Alison's body in order to further sell this image. Now that AI image manipulation has gotten so much better in recent years at rendering bodily animation, could you re-revisit this piece and add some motion that compliment her facial expressions as they evolve from embarrassed self-conscious nervousness to growing admiration of her gen-swapped feminine form and libido emerging from said admiration as demonstrated by her poses in front of a floor-to-ceiling mirror going from almost an adolescent shy virginal girly affectation through clumsily flirtatious coquette to a full-on sultry temptress who's wholly aware of her seductive powers, with her shifting weight on her hips and running her hands up and down her body, turning left and right checking out, as best she can, what she looks like from the side and rear-views, and maybe she even bounces on her tiptoes (or, perhaps she's wearing a pair of extra high-heeled stilettos, which she sashays exaggeratedly while prancing girlishly towards and away from said mirror, catching backwards glances at her backside, admiring the way her shapely naked butt cheeks bounce to the rhythm of her suggestive walk, shown-off as they are by the thongback of those dainty panties that she's modeling. Maybe she even caresses her extra-busty bra-cradled tits, pressing them together to check out her amazing cleavage -- perhaps leaning forward suggestively to further escaate this effect