Those Japanese underground porn magazines we featured here a couple of weeks ago aren't just about wacky covers, you know: if you've been curious to see what they look like on the inside, this extensively illustrated and cross-referenced online resource (which includes lists of urabon by issue date and model) is a good place to start, and there's plenty of links to similar Japanese-language sites if you want to explore further. (Alas, we weren't able to find any pages from "Sweet Panch" or "Pretty Engel"—guess we'll just have to keep looking.)

Urabon Navigator (jans-web.com - thanks Sal)
Thumbnail: Kimi no Hitomi ("Your Pupil")

Previously: Japanese Urabon Covers