Just be up front about the fact that it is part of who you are. That having long hair comes as part of the package.
Honestly, all of the hairstyles I see for most of my fellow teachers and students look exactly the same. Obviously for older students and teachers, it is pretty easy to tell the two apart, but for ichinensei (seventh graders)? I swear, sometimes I have to check who is wearing a skirt and who is wearing pants (the shirt/tie/jacket is the same) to be able to know if the student is male or female until I come to really know the student. The fact that girls are allowed to wear pants if they so wish (which I applaud, yay, Fukuchiyama, now if only the boys could wear skirts if they so wished
) can make this method of identification misleading. Almost all the male teachers all have hair much, much longer than the norm for most work environments, especially the younger ones. And, of course, everyone looks significantly shaggy to my Navy-trained eyes!
Honestly, I don't think it'll be a problem. I do all sorts of "wacky" things, by both Japanese and by American standards, but I never attempted to hide my personality, and the Japanese have been great about taking me as an individual. I think they give gaikokujin a lot more leeway than they ever would a Japanese person, because they realise that all they really know is stereotypes, so they don't know the standards by which you should be judged.
In that way, I feel much freer to express my personality than I ever did in America.
