Can`t be entirely certain on this mark but I think its one of the marks that Noritake used over the years !! It is similar in style to many of their other marks !! The M/K I think stand for Morimura Kumi which just means Morimura Brothers !! They were known for using this type mark !! Noritake is known to have used over 400 marks and while I can`t say for certain,, I am pretty confident this is one of theirs !!