Neat. I can't quite decipher everything that's going on. There are some issues with collision detection and the physics, objects get very jittery when held or left to rest after interacting with another shape. The caustics are odd too, I can't tell if they're reflection mapped or light linked, I'd be very surprised if they were real. I can't read Japanese and the Google Translation is poor, so it's difficult to get good info.
At any rate, it ran great on my computer. ENTER key changes between scenes. F3 temporarily removes DOF, F5 resets the scene. That's all I could figure out. Fun waste of time for a few minutes.
I'd be curious about the use and abilities of the programming. It works well on a small scene with low-poly objects, but how would it do on a large scale?
EDIT
Here's more:
Del/insert - DOF top/bottom
pageup/down - zoom
Home/end - focus?