Okay, this is probably obvious or instinctive to most kendama players, but I thought I’d throw it up for the beginners. A big hurdle that I passed when first learning the kendama is that everything is much easier if you keep the ball from spinning around while doing tricks.
So, for instance, when you’re doing a cup catch of the ball from a hang, you pull the ball up perfectly straight so that it doesn’t spin or rotate as it comes up. This is easier if you get part of your upward motion from bending your legs and then straightening them. When the ball is rotating when it hits the cup, it wants to roll and bounce off the cup. When it’s not spinning, it’s perfectly happy to stay in the cup, which is what you want.
Keeping the ball from spinning is even more important when spiking it. Say you want to do a “tome-ken” trick where you spike the ball from a hang, pulling straight up. If you make sure the ball isn’t spinning, you know where the hole is, right? It’s on the bottom. So there’s one less variable to worry about. The hole is on the bottom, so you just worry about where the spike is and how high the ball is.
Even for something like the “furi-ken,” where you swing the ball the spike it, you need to control the rotation. In this case, the ball has to rotate, but you want it under control. You want the ball to slowly rotate back towards you, around a horizontal axis, so that the hole turns to face you at the right moment. You don’t want random spinning. Again, too many variables there.
For the combinations like the trip around Japan/around the world tricks. positioning the hole is key, so you actually do want to slightly spin the ball to get the hole facing the right direction. This kind of controlled spin is the next step up from preventing a spin.