Ketchup is a police officer in the Dance Valley police force, Sweetland, partnered with Mustard. Their primary duty involves hunting the wanted criminal Nonononn. However, their investigations frequently lead them to mistakenly arrest Padudu due to misunderstandings or misplaced blame. Ketchup holds a higher rank than Mustard within the police hierarchy.
In the 3D OVA episode, Ketchup participates in arresting multiple characters, including Padudu, falsely claiming their two-dimensional nature violates local regulations. During this arrest, Mustard attempts to inform the detainees of their rights but delivers an incorrect and nonsensical statement due to her confusion. This highlights the duo's general ineptitude, despite Ketchup's senior position. A recurring pattern sees Ketchup and Mustard falsely attribute Nonononn's disruptive actions or crimes to Padudu, resulting in Padudu's repeated unjust detainment.