See if your daughter will take a picture of the pattern and a good picture of the marking on the back of the china.
Post it here and I am sure someone can help you.
The word Nippon is simply what the Japanese called "Japan"..
That marking on china was phased out in 1921 when the McKinley tariff act came into being and imported wares had to be labeled clearly with the country of origin....so the marking changed to "made in Japan". So your china was likely made before 1921.
Does your china have a green band with the Greek key design around the top?
Linda C

Hi - I am seniorgal's daughter, I took a few pictures, will see if I can figure out how to post here.

Bottom of cup showing mark

Platter showing pattern,color is kind of aqua:

Cup:

M.

The Nagoya china company was somehow connected with Noritaki and Meiteo ( sp?)...I believe it was made by a company that later became part of the Noritake conglomerate and was made about 1920.
Linda C

Copied from the Gotheborg site......

Nagoya Seito Sho - N&Co, Nagoya, Nippon - Narumi Seito Sho - Meito China
In 1908 Nagoya Seito Sho Company was founded by Kotero Asukai, former employee of Noritake. Other Noritake artisans were soon to follow to teh new company why this porcelain might bear a close resemblance to Noritake porcelain. Their wares was also market Meito China. During the WWII the company was sold and the name changed to Narumi Seito Sho. The Meito China mark continued to be used after WWII with variations in the crown logo mark. Some porcelain with Meito China marks are found with the addition "Made in occupied Japan".

684. N&Co Nagoya Nippon Porcelain. Purchased in the U.S. in the early 1920's

Click here to see large picture