Should I use Japanese title for Japanese people instead of English title?
Assuming you are writing in English, I would say 


The expected* way to address university staff (non-faculty) is
generally "Mr" or "Ms" depending on their gender. 
You can call
people who you would call sensei in Japanese by [family name]-Sensei
(note the position of the sensei as after) in English. 
Calling people with doctorates "Dr X" is not generally expected in
    Japan. (Also, many Japanese faculty who are older don't have doctorates due to some vagaries of the system used here).
Similarly, they are much less used to "Professor X" than
    in American contexts. 


I would say (2) is normal in day-to-day conversation, but for many of them writing = Mr / Ms

Separately, if he is truly "support staff," then he is not a sensei within the Japanese system. If he is over the support staff, that might not be true.



*by "expected" I mean the expectation of most Japanese users of English

Source: 1kyu (JPLT N1) and presently living in Japan working at a university