No Export for You: The Sega Ages 2500 Series Vol. 31: Cyber Troopers Virtual-ON for the PlayStation 2 was released only in Japan, and it's considered the best port of the original game thus far, much to Western fans' dismay.
Virtual-ON: FORCE for the Xbox 360 is also a Japan-only port of the series' third installment, but thankfully the game is region-free, making the game import-friendly... if you're willing to spend a lot of money for it (depending where you're importing it from), especially the rare MEMORIAL BOX 15premium package.
Operation Moongate's Model2 Collection re-release on Xbox LIVE Arcade and PlayStation Network is also Japan-only, which has HD graphics surperior to the Sega Ages 2500 Series version on PlayStation 2. Needless to say, some people are pissed about this.
The PlayStation Network re-release of MARZ also got this end of the stick. Thankfully for those with Japanese PSN account and access to Japanese currency can play MARZ without the laughably bad voice-overs and removed content from the US PS2 version.
Sequel First: If you live in Japan and have an Xbox 360. Oratorio Tangram Ver.5.66, the game's first sequel, was re-released in 2009 world-wide; Operation Moongate's Model2 Collection Japan-only re-release showed up February 13th, 2013.