She can't hold it

The mere sight of the library made Mai relax a little, causing a loud fart, followed by a surge of diarrhea to sneak into her panties.

Mai stopped in shock. She couldn't believe she had shitting herself, being so close. Another wet fart brought her back to reality, causing her to squeeze her buttocks once more.

Mai couldn't move. If she did, probably the poop that was in her panties would spill out and there were people passing by who could see her. But if he did nothing, what was left inside would come out.