Hello Kitty is a fictional cartoon character created by a Japanese company Sanrio. It is essentially a female kitten with a red bow on the head. It is one of the most popular cartoon character in Eastern Asia, particularly in Japan and China. The kitten is said to be very cute (in Japanese, Kawaii). It attracts children in particular. There are Hello Kitty theme parks in Japan and different cities in Asia. A special feature of Hello Kitty is that it has no mouth (unless in animation where “she” needs to talk).
Learn more about it by reading the Wikipedia entry of Hello Kitty.
Unfortunately these are the only Hello Kitty Chrome themes available in Chrome Web Store. So I turn to other unofficial Chrome theme sites and found the following good stuff. To install, you need to click Install or Download on the web site, Chrome would ask you if you want to save it or discard. Click Save, the file would be downloaded and installed automatically.