I worked at Yokota RAPCON a couple years ago for a little while and my experience with Kastner is very few IFR ops and not that many ops in general, all helicopter. The airspace is basically a small cutout of Atsugi naval airbase's airspace that is south east of it. I only went the base once but it is small and comes with what a small army post consists of, PX, gym, a club but they also have grounds for camping and outdoor activities and golf course. I would assume facility is pretty chill cause every time there we gave them an inbound they sounded like they just woke up from a nap.