Your damn step-sister has come used your computer every day since you shrank and not once bothered to check the seat. Everyday she plays your games and gets so excited that she starts slamming her giantess ass on the seat, right where you are! She's gotta notice you eventually, right?
See video here:
https://www.patreon.com/posts/64480914
https://www.patreon.com/posts/64480914
Sidenote: if anyone knows who she is please let me know so I can give her credit and maybe find more similar videos to edit and continue this series.