Ryonas are actually good if placed correctly in any situation. I'll just put my priorities on top and give a few examples.
1. Modern
Basically i love the real deal, i love how girls are dressed nowadays, and i simply want to make them suffer in the time where i live now. In the modern world, i know how the weapons are used for, guns, knives, etc. Plus, it's easier to imagine you pummeling a girl in a situation you're used to live with.
2. Fantasy
Trolls, ogres, monsters, whatever you name it. In this dimension it's much more physically brutal rather than effective (like guns in modern). They use muscles, sticks, giant bats or anything that can wreck a girl's skeleton. For example, a dragon can stomp her, munch her or even burn her. Ogres bearhug, crush her skull, ar even smack her with nis gigantic bat. Bloodsuckers, tarantulas, land octopuses or tentacles, everything beats the girl physically. Unfortunately though, this world offer clothings that i don't seem to like much.
3. Sci-fi
Yes, robots. Put her between 2 moving gears and watch her crushed. This world offers pretty good ryonas with set of booby traps. Laser guns, as long as they only leave burn marks, is pretty good for some punishments. Not to mention electrocutions and spikeshooters. One of the best robotic sci-fi punishment i've seen is cracklecradle's level 3 enemies.
It's up to your imagination, actually.
