They say that an image is worth a thousand words, and I bring you three of this theme made by mcder3 :
The most positive thing I see about this theme is that it relaxes… it has an “air” or atmosphere of peace and tranquility that we often need
You can download it from the following link: Download Kotonaru Theme
Once downloaded, they unzip it and copy (what was unzipped) to ~ / .kde4 / share / apps / desktoptheme /
Now the final step, activate it
For that open the System preferences, go to Workspace appearance, Desktop theme, and there they select it
Personally I would change the background, but I like the colors…
Greetings and enjoy it