[Sangetsu]

Obviously the OP doesn't need if for medical reasons, after all, he said he "isn't going to touch the stuff" while he is in Japan.

Marijuana stays in your system much longer than other substances. You would need a hair cut and to be clean for at least several weeks before a test. You might also expect the tester to have a sense of humor and take a hair sample from your leg, armpit, or chest, rather than from your head.

On the other hand, "random" generally means "almost never", and the few people I know from Interac have never been tested.

While in the Army, I worked for a time at the FDTF, and their testing methods are quite thorough. If you have used drugs at any time in your life, they will find out. There has been talk of using their methods more widely, and private companies have expressed interest, but who knows when it will happen.