Last trip, I had a lot of free time in the morning so I went to every possible DVD/Adult Store in Akihabara and Ikebukuro to see if I can find something rare. They're open surprisingly early and what I found out was that most DVD places only have a small selection for Magazines and it's usually the latest stuff released. Some of the magazines are also just a few pages with a CD stuffed inside them. You might have luck in some of the ones that sold more secondhand stuff, but it'll probably be either overpriced or not popular.
I don't know how to exactly give you the search prompts in google maps, but use these links and click the description of the place located under the ratings. That will bring up all the other places under the same tag.
https://maps.app.goo.gl/to7vcFj4JzHkXHx28
Click [Adult DVD Store]
https://maps.app.goo.gl/9pqHrGiLHnjjvSHp9
Click [Adult Entertainment Store]
https://maps.app.goo.gl/6rfCwzRECLvyDDJY8
Click [DVD Store]
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I bought a couple of DVDs that had signed polaroids and promotional pictures bundled in with them of some girls I follow. The only magazines that caught my eye were Posing Magazines of JAV Stars and Cosplay/Stocking Fetish ones.
However, near akihabara station and next to some vending machines there was a building where on the third and fourth floor (I can't remember if it was even on Google Maps) there was an interesting store that specialized in niche interests (voyeur, watersports, urination, ryona, etc). The staff there were just glaring at customers while neatly wrapping dvds at the counter. I didn't want to just abruptly leave so I pretended to be very interested and trying to look for something in particular. Oh, did I forget to mention all the used underwear and costumes stocked on the front shelves right next to the entrance?
Needless to say, I saw one guy come in and immediately noped right out. lol
