This is a relatively new company, first appearing in the Chinese market in about 2016. They are apparently a sub-heading of a larger pen maker, Shanghai Jingdian. It’s very hard to find anything on either brand in English, so I don’t have a lot more to say on the topic.
According to this fellow, the characters used for “Moonman” in Chinese have nothing to do with a large satellite and its inhabitants, but rather translate as “Last Craftsman”. This feeds into the freshly-grown mythology of the company, about it having been begun by a small cadre of pen enthusiasts who happened to also work in a pen factory. Their focus is apparently upon making pens which are inexpensive without them being cheap. Since they appeared, they have proven extremely popular, so they must be doing something right.
Models I’ve examined: