Akko, the Berry Big Bunny (Patreon)

One day, Akko, just fresh off of learning how to fly on a broom, came across one of the new students aspiring to be a witch like her. "Oh, hello!" She shouted, eager to meet a new face. "Are you one of the new students?" In response, the mute, shy girl could only nod, barely able to even look at her new chatting partner. "Well, great! I may not be a professor, but I'd like to help you get a head start!"  Before the girl could even get a chance to respond, Akko continued.  "Let's start with magic practice! Here, just borrow my wand!" The bouncing brunette promptly handed the newbie the little magic device, before stepping back.

"Let's start with something simple! Think of an animal, and-" She's promptly interrupted after the new student already cast a spell in a fit of panic and  pressure. Of course, it just so happened to affect Akko in the sense that it changed her partway into a rabbit. Akko got annoyed towards  this, pouting at the memory of the last time this happened. "Not  again..."

 "Okay, let's try again. Let's try...Making a blueberry bush! Just picture th-" However, the shy spell caster immediately cast a spell before Akko could finish yet again. Clearly, she just wanted to get this over with as quickly as possible. "...You didn't just cast it on me again, did you?" The poor girl could only shrink from the look of shock and surprise Akko gave her, before she noticed something about her fellow student's rabbit nose. Was it turning a bit blue? And...were her cheeks too? For reasons unknown, Akko didn't notice at first. She only started to realize something was up when she could feel her wand holster tighten around her waist. She looks down, seeing that her belly is growing somehow! As if that wasn't humiliating enough, it seems her butt is joining in on this growth. "Wait...What?"

 Before Akko could take in what was going on, a deep gurgle emanated within her belly.  A second afterwards, it surged out in growth before whatever was filling her started to spread elsewhere, her body becoming more and more blue.  Her hips and legs became thicker and thicker, her calves eventually getting too big for her boots and causing them to split. Her body sloshed as she did her best to keep herself from falling over, and the fact that her arms and chest were starting to fill wasn’t helping much.  Seeing just how big and fat she was getting, all Akko could say was, “WAaAaAaAH!!!”

 As Akko continued to bloat and swell, the shy student started to back away, not sure if she should stick around.  Not only because she could go and possibly get help, but also because was reminding her more and more of a balloon.  Her arms and legs were not only getting thicker, but shorter as well, as if her body was absorbing them. Her uniform, while doing decently well, was failing here and there.  Her boots were torn down to the ankle, and as her chest continued to fill, her tie became undone and the strap on her dress eventually snapped apart,  Akko’s wide frame and full bust being far too much for it.  Despite wanting to go and find someone, however, her feet would not move as Akko’s growth came to a close, leaving her a wide, blue orb. The swollen witch looked to be rather stunned, as she only managed to mutter out, “W-Why is this…”

 After a solid minute of just sitting there, Akko let out a breath before letting a nervous smile form on her lips.  “O-okay, I think it stopped… No need to bring this up to anyone, okay?” While she was still unsure about… just about everything now, the new student gave a small nod.  “Good! Now, just need to find a way to get rid of all this… weight?” Pushing herself up with her feet, whatever had made her so big sloshed about inside her. Thinking about it, it was probably blueberry juice, but that really didn’t matter right now.  “Okay, um, just do what you did before, think of something nice and light-” Before she knew it, the other witch cast a spell before looking like she made a grave  mistake. “...What did you-” Before Akko could finish her question, she started to grow again, becoming taller as well as wider.  This time, instead of wet sloshes and groans, there was an almost ominous hiss that could be heard coming from inside her. Just as Akko’s cheeks started to become fuller, the big blue rabbit of a witch started to float, her feet and body leaving the ground and leaving her even more helpless as  she started to float towards the skies.  “Oh, come on!”

 “O-Okay, m-maybe this isn’t so bad???”  Akko tried to reassure herself, though she told herself mentally that it was for the shy student down below.  The giant blue balloon rolled in the air as she kicked her feet and flapped her hands, her ears flopping about uselessly as well.  As the ground got further and further away, she continued to blow up bigger and bigger, her immense form quickly becoming noticeable to just about everyone around, becoming larger than some of the lecture halls at the school.  As she continued to stretch and fill, her already plump cheeks become fuller as well, quickly looking as though she had stuffed a pair of grapefruits through plumped lips. As her body continued to hiss, groan, and even creak, one word described how Akko felt as she continued to fill: Full.