Don't think it is either, just by the general style. Since this is a Taoist diety, it is common to several Oriental countries although the artwork looks Japanese to me. The text is in a script common to both Japan and China, so that doesn't tell me anything. Potter's marks would help on the underside.

The mark certainly suggests it was either for export, or for sales to foreign market stationed in Japan. Did any of your relatives do a stint there on active duty with the military? It looks to be a nice quality, and I am not at all familiar with the maker, either. The only thing I can add to the comments are that it's not unusual to find tea sets actually sold in the country of Japan to have a setting for five. It doesn't mean that it's less than a complete set (like for six or eight). When my mother would go marketing or buy china, it was pretty common for the vendors to throw in a freebie to bring the number up to five. I have several sets of china meant to be sets of five. It was an auspicious number.

The set with the blue handles and "made in Japan" on the bottom is most likely from the mid 40's through the 50's. Made in Japan became in common use, substituting for just Japan" on wares that were un marked with a maker's name beginning in 1941. The second set is the Moss Rose pattern....made by many potteries, including CF Haviland, J G Meakin and others. It has a maker's mark but I can't read it. Because it says simply Japan I am guessing it is early 20th century....and if it's a child's set and complete as it appears to be, it's very desirable!! Lots of people love Moss Rose....guessing it might bring $200 at the right auction.

It's mid to late 20th century, but I don't know the name of the maker. You could do a Google search for mid century japanese china makers.