Sad, Sad Santa is the 50th chapter of the Dr. Slump manga.
Summary[]
It is Christmas Eve. Senbei Norimaki, disguised as Santa Claus, gives his autograph to the residents of Penguin Village: Arale Norimaki, Akane Kimidori, King Nikochan, Kurikinton Soramame, Kinoko Sarada, and Midori Yamabuki. The next morning, Midori is angry at him for entering her apartment.