You're an intern at Mirukos agency, you just joined and were eager to prove your worth to her. But you have a problem, you're a tiny. In your world, besides quirks and quirkless; there's also tinies, who also have quirks or no quirks. Your quirk made you strong enough to get you into a hero school, despite your stature.
"So, your the new guy; the intern?", Miruko asked. You were standing on her desk, in her office. As you nod to her question, she sighed. "Look, I don't normally take interns; but your the first tiny to get into UAs hero course, so I naturally wanted the opportunity. But I'm not sending you into real combat yet, just so you know", she explains. You nod in understanding, as a phone could be heard. "Excuse me", Miruko opens a drawer and pulls out a phone and leaves her office.
Curious, you peek into the drawer. You see a butt plug with a pattern just like your costume, when you leaned to far and fell into the drawer.
"Wait here rookie, I have business!", Miruko rushed in and reached into the drawer. She had intended on grabbing the butt plug, but unknowingly got you. She had this plug to keep from farting while she fought villains. She went in her bathroom, and quickly put in firmly in her anus.
"Let's go!", Miruko said as she rushed outside. You were in for a wild ride, as your body was stuck; your arms pinned to your torso by the anal ring. As Miruko got on a motorcycle, she felt her stomach rumble. "Early ain't ya?", she asked her ass. She felt her first fart, but her butt plug blocked most smell and sound; doing its job. But you smelled it; as the stink was trapped, it began to fester.
Miruko was eager to kick butt, as she got close to the first villain. He seemed low level, so this should be easy. "Lucky flying kick!", she beat him immediately. As she landed the kick, her anus almost squeezed you to death. "One down, two to go", Miruko said as she got back on her bike.
As she drove, she let out more farts. The first was near unnoticeable to you, but still added to the smell. The second was hot, and almost steamed you like a vegetable. Then it was a trio of firm butt bombs, that physically hurt as the smell worsened.
As Miruko got into fisticuffs with the second villain, it was a series of farts as she got worked up; excited by the challenge. But in the end, she still won. "Lucky punch!"
You weren't sure how many more farts you could take, as you felt them pound you; each one adding a new scent to the buffet of smells.
As Miruko got her finishing move in on the last villain, she lost balance as she fell on her butt. Then she felt her butt plug shoot inside her. "Crap, I'll deal with it later", she said. Driving back, her farts were much louder.
As she walked into her office, she walked up to her drawer; and noticed something. Her butt plug, in the drawer. As she tried to figure it out, a thought came to her.
"Where's the tiny intern!?", she asked everyone. After nobody knew, she felt it.
"Great, off to the hospital then", she said.