Re: Problems in a dojo
You are in a difficult predicament. Attention to detail can provide you with a lot of clues as to where to go from here.
1) Look around at other schools in your area and ask yourself if this particular sensei is so much better than the others in your area that you cannot "afford" to leave this training opportunity. If the answer is "no", I see no reason why to engage in such a masochistic process.
2) Japanese culture usually allows for the social influences to balance out the "nail that sticks up." If the teacher is not Japanese, or is not very traditional, then the teacher is clearly failing in the responsibility to create and sustain a safe training atmosphere.
3) If you choose to stay, you can simply avoid working with that person. If confronted by that person, tell the person that you are there to train with people who are interested in helping you learn.
4) If you have to work with that person, as uke, be as soft as humanly possible and exit early in ukemi so that the person does not have an opportunity to be intentionally hard. This tactic usually results in that person not wanting to work with you. As nage, if the person refuses to allow you to complete the technique, stand there and ask for his assistance in helping you to be able to complete the technique as nage.
5) You can be up-front with that person in an open manner. You can tell this person that you are eager and open to learning, but that for some reason, you and he do not seem to work well together. He as the senior student, has an obligation to help you learn, and you would want to know from him, why this is so difficult for both of you. Ask directly, what both of you could do to improve the situation.
This person may not change, despite your best efforts. This is an opportunity for you to see how you can avoid conflict. If conflict is inevitable, then simply do what you must to stay safe. If the situation becomes a real risk to your personal safety and the teacher does not protect the students, then find training opportunities elsewhere. This path of budo is a LONG path with many options. Be patient and do not fear trying other directions.
Best wishes for a safe ending to this bad situation.