I would say for soaps generally avoid saying you are from China...if they ask just say you are Singaporean/Malaysian.
In terms of language, I find that even with JLPT N1 and living in Japan for a few years the reception/tout can still deduce whether you are gaijin or not. Basic lessons simply don't cut it as a lot of keigo is generally needed. This automatically rules out a lot of soaps in Japan. And even if you get in there is less choice for us gaijins.
I would say the best bet would be to go with your Japanese colleagues (male, preferably
) or better still with a regular of the scene there.
Also, soap is super expensive in Japan and I would say there is not much value in the lower-tiered ones except for the thrill of bonking a Jap chick. But there are decent options like Darling Harbour and Naniwa which offer great value should one be inclined to look for it (google is your friend).