"Sirotan" is a merchandise character made by Creative Yoko, similar to Hello Kitty (by Sanrio) and Afroken (by San-X).
"Sirotan" literally means, "Widdle White," the childish version of "Little White." [more information]
Sirotan is the name for a cute little young harp seal who loves to disguise himself as various sea creatures among other things.
Thus, the main type of merchandise sold are plushie versions of Sirotan with removeable disguises.
However, with the popularity of the Sirotan character, hundreds of other types of merchandise featuring him are sold, including cups, cell phone accessories, pillows, lunch sets, toys, bags, children's books, a sushi set, and so much more.
Sirotan comes in many different sizes with the respective sizes of disguises. The biggest size is like a pillow (with a length of about 21 inches), the medium is plushie size (with a length of about 8 inches) and the smallest is a keychain size! There are also some variations in between.
Disclaimer: Sirotan etc. is copyright by Creative Yoko. I claim no ownership to him or any of his information.