Shiro wants to be an utterly serious, self-reliant ninja type. She hasn't yet realized that the universe is determined to make her comic relief, and she will stubbornly resist being made into the class clown every step of the way. Despite her serious frown, every aspect of her, from her ridiculous armor, to her more ridiculous transformation, to her purple walrus companion is designed for somebody who is at the center of attention at all times. She is completely unaware that she's barely more subtle in her regular form, and blames any negative attention she receives on her transformation into Radiant Clown.
Truth be told, Shiro is probably rather lonely and doesn't yet know how to connect to other people. All she needs is a good set of friends to help her not lose her way!