Requesting Chie Satonaka taking a much-needed forceful standing piss like top right but spreading her pussy with her fingers and with a lewd, relieved expression. This would be in the Samegawa Flood Plains (location bottom center), but if you're not up for drawing backgrounds, just her pissing on a tree, rock wall, or into a river is fine. An alternate angle from behind showing her butt would be awesome, but optional.

Also optionally, context is she forgot to relieve herself after a long day of training and staying hydrated/eating a lot of juicy meat, and there's no time to get to a toilet. If you're game for drawing that, you could do it as a flashback like in bottom right.