GOD you can't just post shit like this and withhold the source for ELEVEN MONTHS
Thanks to @dog for pointing out this is from Futari H / Futari Ecchi. Great shall be your reward in heaven.

30 | Game Designer(?) | Arcade Lover | KOF Hippie™ | Ascended & Unhinged Sonic Fan | Sudden Onset Touhou Fan (it's terminal)
GOD you can't just post shit like this and withhold the source for ELEVEN MONTHS
Thanks to @dog for pointing out this is from Futari H / Futari Ecchi. Great shall be your reward in heaven.
I only watched the anime, but Futari Ecchi is pretty good, as like, a realistic instruction manual for having real (cishet) sex with an actual person!
i'm thankful someone knew, because i had completely forgotten and was ALSO mad at myself for not having the source