Maybe they were released in the West through Limited Run Games or some similar company, but I believe these are at least easier to find in Japan than in other countries:
Game Tengoku CruisnMix [ゲーム天国 CrusinMix]
Darius Burst Chronicle Saviours [ダライアスバーストクロニクルセイバーズ]
Raiden V - Director's Cut [雷電V Director's Cut]
Psyvaria Delta [サイヴァリア デルタ] (This will be released on August 30th)
These are the ones that come to my mind now... If I remember anything else, I will send here.