You will quite often see these Kanji on the right hand side of the marking, denoting that the item was "made in Japan" or of Japanese origin.I guess that it is just a hallmark to show where the item came from or a way of the maker announcing that they were from that place.Another way to find the marking yourself is to look at the large list over that the Gotheborg website.I often look there and scan the list of markings, trying to spot one that looks the same.If you see a piece with this written on, then you can assume it will be from the Meji period (1868-1912).Most old and authentic pieces of Satsumaware will have the Shimazu family crest on, usually at the top of the marking (the red circle with the cross in).Sometimes, the marks at the top can be hard to identify as they are quite small and have been created by a brush.This part of the marking means "to made" or "to manufacture" but can also mean "made by" and is often the last kanji on the marking, written in the bottom left corner.
However, due to the fact that it is quite a detailed kanji, it can sometimes be hard to identify properly.
I often refer to a Kanji online system that allows you to build up the symbol piece by piece to make the word.
This can take a little practise though and does not always give good results - especially with hand painted markings and definitely when it comes to people's names.
This mark shows that the pottery was made under the rule of the Shimazu clan and is a good way of determining if the item is of value.
The crest is always found at the top of the cartouche.
Again, this takes time and can make your eyes hurt, but will be worth the effort.