Mushihimesama Futari is a vertical STG developed by CAVE. IT had an original release in arcades, then a 1.5 version and Black Label were released. There was also a 360 port with Black Label available as DLC. CAVE released it region free to test international waters. It seemed as though international sales exceeded expectations, however it is a shame not so many people have played it as it is a real gem. There is a "Platinum" release around the corner, I haven't seen a confirmation of its status in regards to being region free yet, but I will be sure to let people know. I love the game so strongly, I may even buy a few copies to give away (under the assumption it is region free).
Basically, it is a vertical shoot 'em up. It has 3 difficulties, Original, Maniac and Ultra. Original and Ultra have somewhat similar scoring systems (switching between shot and laser depending on your "counter" at various intervals), Maniac being somewhat more complex. For me, I really love the scoring system. It is straight forward, but at the same time it adds a real challenge to the game and adds substantial depth.
There is always quite a lot going on. It may be danmaku or giant boulders but there is always something to keep your eye on. From stage 3 onwards and stage 5 in particular, it becomes so fast paced and hectic you will probably surprise yourself at how you weave through the various patterns. It is a hugely rewarding and challenging game, and the Black Label DLC adds a huge amount to it. It is one of my favorite STGs. I play it damn near every day and recommend it highly.
I will add a video from the game and also the CAVE MushiFutari (Black Label)/Deathsmiles Superplay. Shmup videos always make it look easy ;_;. Most of the time anyways..
In other news, another DoDonPachi DFK PV has been released from CAVE. Coming out Nov. 25 for those of us with J360s.