Re: Scared Sempai
I would advise compassion. Although it may be frutstrating to you, you never know why someone is so fearful. To this person, taking ukemi, letting go is scary. We all have our weak spots, no matter how senior, or how junior, so try compassion. You just don't know how he feels. For one person, taking ukemi, or aikido is easy. To another, it's the scariest thing in the world.
It can be frustrating, though. That's what is so good about aikido, the encounter is always a challenge, and there are so many levels, not just skill in the challenge.