Hi Hi Puffy AmiYumi (2004)

S3E26 Gridiron Maidens

Ami decides to join Kaz's football team, unaware of the risks involved in the sport. To protect her from Yumi's interference, Kaz instructs the security guard to keep Yumi out. However, Yumi manages to sneak in dressed as a cheerleader. Recognizing that Ami is struggling against the competition, Yumi steps in to lend a hand, all while keeping her identity a secret from Ami.