Even original homebrew ROMs that don't infringe on existing copyrights exist in a legal gray area. While creating emulators is legal, distributing copyrighted game code is not. Many hentai ROMs borrow from commercial games, making their distribution questionable at best.
If you only take two titles from this list today, make it these: Hentai Gba Roms Zip
A handful of legitimate adult-themed or risqué Japanese games were released for the GBA, though they were never sold in Western markets. Titles like Hajimete No Orusuban were described as "Digital Comics Hentai" when they were imported. You may also find unofficial English translation patches for these in .zip archives. Even original homebrew ROMs that don't infringe on