You can go to the following website to read about a review of the Kawai KX21 upright piano. They have done their review by playing on this piano and have written a pretty good review and provided a rating in various categories. Go to
www.pianosonline.co.uk/Then click on "Pianos Online Reviews" . You will see this menu choice appear to the extreme left-hand side on this website. You should then scroll down until you see the section with Kawai KX21 listed and then click on it. You see the review and ratings.
The KX21 is made in China and it is 48 inches in height. I believe that the KX18 is shorter. The finish of the materials used inside the piano, the hammers and the felt used are not as good in quality and workmanship as compared to, for example, a Kawai K50 made in Japan.