There's no specific date of release, but is is confirmed to be releasing in July (late July according to DLsite).
There is also a demo up. Gameplay-wise, it seems pretty much the same as the original game. Though there is an airborne enemy now which I don't recall having any in the first one. So perhaps the newer enemies will also be more varied. The boss seems a bit confusing to me. I attack the chain constantly but it seems to do not much damage, if any. Meanwhile the elf charged attack takes a big chunk of the hp. The battle is also quite busy since there are now 2 supports constantly throwing out charged attacks. It plays a flashy and nice looking animation each time they use it. Looks nice the first time, but kinda annoying after 3-4 times when I can't fight without being interrupted by a 4 second long animation.
The demo has combat rape with 2 new enemies. As usual, you enter a "gallery" with the stage enemies when you die before the boss. This time Saya (new char) will be the other character being raped. One addition I like is that you can now zoom in during the gallery. Hopefully the full game has an alternate camera gallery with the other characters. I mentioned before how only the elf girl had this option in the previous game. Losing during the boss fight also has an h-scene as before, however it is not included in the demo.