Before Korea conquered the world with MMOs, bringing games to overseas markets used to be not only a status symbol for Korean developers, but also a way to escape the limitations of the comparatively small Korean market, where games where always pirated more often than bought.
Japan was a particular popular but hard-to-get target. Popular because Japan is the country with, like, the lowest software piracy rate in the world, and because of a sense of rivalry with the then world leader in video game production; hard to get because of different computer standards (mostly PC-98 until 1995, thereafter Windows 95 while most Korean games were still DOS-based for about two more years) and because the Japanese PC game market is [exaggeration] almost exclusively an adult game market unless you're Falcom[/exaggeration].
The Koreans did their best to overcome these problems, by porting their games to Windows primarily for Japanese export, like Phantagram did with Zyclunt and Softmax with Aimpoint. Yet popular games like Zyclunt and Softmax' The War of Genesis still ended up with extremely niche publishers no one has ever heard about, others like Aimpoint seem like they didn't even make it that far. In later years reasonable success on the Japanese market always seemed to mean - no big surprise here - to team up with Falcom, like Rhapsody of Zephyr and Arcturus showed.
But there was also another way - some companies figured to get games onto a market that's dominated by adult software, they'd just have to fill up their games with adult content.
Warning: While this post doesn't contain any particularly nasty images, it might still be just ever so slightly NSFW if you're working for a very serious superior.
Such a game is Xenoage. Developed and published by Gama Soft in Korea in 2000, the game originally is a perfectly harmless SRPG in cute anime style graphics. When famous-infamous eroge producer Xuse picked up the game for publication in Japan, however, it turned out an entirely different deal.
Now titled Kaze to Daichi no Pageant, the game came with a significantly changed plot, where of course the protagonist gets to woo pretty much all the ladies that show up in the game. But that's not where the changes end, in-engine cutscenes are replaced by static images, even when there are no hentai scenes around. Dialogues are accompanied by character portraits now redrawn in a more Japanese style, with even a few new ones for characters that previously didn't have any lines to speak, mostly female ones. While the sprites are mostly the same, battlefields have been re-rendered. Oddly enough, they still resemble the original ones but look worse in most cases. The ingame map has also been mirrored and altered for whatever reasons - maybe because volcanos are cool. Besides all these cosmetic changes, the Japanese version is also significantly easier than even the lowest of formerly three difficulty levels.
Xenoage was not the only occasion where a Korean game was sexed-up to sell in Japan, though. The next example is at the same time a call-out to any experts of Japanese PC games. It is named Newly Weds and developed by Ecstasy Entertainment. Already a slightly "sexy" Princess Maker clone where in place of the princess is the wife of the player character, Newly Weds contains several images that clearly betray the artists desire to actually draw them in a more naughty way, sometimes they even look like they're edited from a more revealing original.
Ecstasy Entertainment announced that they would produce a Japanese version with nude imagery, however a publisher was never named. Either the Japanese version never came out, got its title changed and/or got an even more minor release than earlier Korean games in Japan. The Korean title would read 新婚日記 in Chinese characters, but such a game doesn't seem to exist in Japan. Here are some more screenshots, should anyone have ever seen this game in its Japanese version, please comment.