Anyone know the original?

Yeah definitely not Boku no Pico. An artist named nikciB animated some of Rankou Kyoushitsu by Po-Ju, and drew some alternative scenes.

Doujin here:
https://myreadingmanga.info/po-ju-rankou-kyoushitsu-promiscuity-classroom-eng/

nikciB's additional illustrations:
https://chan.sankakucomplex.com/?tags=nikcib

Yeah definitely not Boku no Pico. An artist named nikciB animated some of Rankou Kyoushitsu by Po-Ju, and drew some alternative scenes.

Doujin here:
https://myreadingmanga.info/po-ju-rankou-kyoushitsu-promiscuity-classroom-eng/

nikciB's additional illustrations:
https://chan.sankakucomplex.com/?tags=nikcib

Her name is Pico from Buko no Pico. U dont find that anymore in hentai sites but u could find it in unsupervised sites.