Identify Old animation

[Punkreas]

Hello everyone, first of all sorry if this isn't allowed on F95, but since this is my main hentai forum, i'm here too looking for the name of an old animation.

The first and only time that i saw this was around 2003 maybe 2004 in those small pieces on free websites back in the day, its a video where a boy/guy was watching a woman (probably his mother) doing other guy on a hot spring, he's hiding behid bushes/fence while watching her, its a very vague description but any hint will help

Thanks !