3x11 - Shugo Chara!

Hikaru's Grandfather gives him a brand new fountain pen, as a gift for joining Seiyo Elementary School, but he says he doesn't use a fountain pen but keeps it anyway. Rikka loses her special treasure, a necklace that her dad gave her when she entered elementary school, and is desperately retracing her steps in order to find it. Amu and her Guardian Characters all help Rikka out, but Hikaru doesn't understand what all the fuss is about. Hikaru can't comprehend how something as trivial as a gift from someone can be so precious. Amu and her Guardian Characters help Rikka to find it. At the end of the episode Hikaru puts the pen on his pocket, when his grandfather sees it he becomes very happy and Hikaru smiles a little too.