In spite of my general prejudice against Japanese games (it's not a personal thing, I'm just sick of VNs in general and VN plots in specific), when they actually get around to making porn RPGs they can be pretty sweet.
In that spirit, I have some recommendations.
1) Panic in Cobra City: Cobra Mission. Available here:
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First and foremost, this game is OLD. I'm talking literally 1992. But you can run it in dosbox, it's freely available abandonware, and honestly...it's actually a pretty decent game. Graphics are a little basic but the available color palette (not sure if it's 16 or 256 colors) is generally enough to make things work when the actual porn happens. Plot rundown: you play a detective who's investigating...I think a series of kidnappings? In a weird city run by mobsters. It's sorta noir-ish, and you start with a gun, but you very quickly run out of ammo and find out that you need to switch to melee weapons instead because the town heavily restricts ammunition sales. It's a top-down RPG with first-person-style combat, fairly basic stuff, but there's actually both a decent game and some pretty advanced porn stuff that happens. A little more focused on BDSM than I prefer, but there's a combination of still images and an arousal-sex-type game in the hotels. Overall, pretty sweet. Definitely use a walkthrough if you want to complete it.
2) Brave Soul. Thankfully there's already a thread here:
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Also a pretty unique RPG, it's kinda like Diablo meets an idle game in a certain way: you wander around, gather up cash and materials as your character kermashes their enemies pretty much automatically, and go through events to get your character laid. Much like Cobra Mission there aren't aaallll that many porn scenes, but it's actually very replayable (I think it's like a half-dozen different replays to get every ending), there's a New Game plus mode, and...yeah. Legit kinda fun. Technically you can play through it yourself and make progress, but I'd recommend a walkthrough if you want to get some of the more difficult girls. Honestly, I have half a mind to play this one again now that I'm reminded of it. On a sadder note: while this actually did pretty well in the States when translated (full English release! Not machine translated!), it seems that the Japanese fucking hate fun, good porn games. Not aware of any actual sequel, depressingly.
3) Eushully games. Generally speaking, I have a rule: I don't play untranslated Japanese games. Eushully, however, makes the best fucking Japanese porn RPGs I have ever tried. To be clear, not every game they make is actually the sort of thing you seem to be asking for. However! They have two very solid ones that are worth looking up.
First: Tayuuta (Eushully wiki for the game
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, includes scene guides and characters, etc.)
Such a good game. Ridiculously deep turn-based dungeon crawl, lots of fantasy game tropes, weapon upgrade systems, even seems to be at least a partially upgradable house. Fucking enormous game. The art is great and, if you can figure out how to handle at least the interface with a text hooker (yes, I know, sigh), it's most definitely a game that can suck you the fuck in. I don't have a link, but I imagine you could find one.
Second: Arterial of Origins. F95zone page
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Partially machine translated. Again, it may not be your scene due to language issues, but it's also a very deep RPG with card battle-based combat this time. Lots of (yes, granted, kinda stupid) story, lots of characters, something like 9 endings. It's pretty much as Japanese as you can get, but done so incredibly well and such an interesting RPG in and of itself that I'd feel remiss if I didn't mention this one.
For these last two, you pretty much need a text hooker though to get through them, and I only recommend them because of their sheer quality.
Damn it. I could swear there's another one rattling around in my brain somewhere, but that's what I've got. Seriously though, even if you don't try the Eushully ones, Brave Soul and Cobra Mission are both definitely worth a shot. But Brave Soul is probably the easiest to get into and the one I can most easily recommend as 'fun' in addition to being decent porn.
