1. I'm not all that sure how much Chinese customs/immigration people are going to care about what some Canadian therapist writes on a scrap of paper (and you're making a hell of an assumption that they are going to be able to read and understand English that well in the first place.) That's it's legally got some value in Canada or the US, does not make it relevant in China at all.
2. I'd strongly urge you to go to the Chinese consulate and see if you can work it out there, and be prepared to have your company and yourself take it all the way to the Chinese Embassy.
3. Don't assume that the problem is only going to be in China, Japan is very, very picky about who they let in.