Brand new Rilakkuma Nintendo 3DS themes released today in Japan what you can buy from the Japan Nintendo eShop.
You can get the normal “Rilakkuma” and the “Rilakkuma Relaxing Cat” version for 200 – 200 Yen (with tax) (Package price not available),

Both of them comes with normal wallpapers, sound effects and BGMs. You can watch in here the official introduce videos: