Cells at Work!: The Common Cold

Tired of repeating the same task (cell division) day after day, the Normal Cell laments while working his boring job, when a mysterious cell wearing a charming hat suddenly appears in front of him. This cell proceeds to invite the Normal Cell to spread mischief and play pranks on the White Blood Cells (Neutrophils) and Killer T Cells. Though the Normal Cell enjoys being able to blow off some steam from his day to day life, who is this charming hat wearing cell?