Mio Tezuka is a supporting character in the anime Moetan. She is the younger sister of Nao Tezuka and a school-age student. Mio has brown hair worn in pigtails and green eyes. Her personality is energetic and perceptive. Although she pretends to be unaware of Ink Nijihara's secret identity as the magical girl Pastel Ink, she can see through the disguise and knows the truth. Mio is supportive of the idea of Ink and her brother Nao becoming a couple, and she secretly tries to arrange situations where they can spend time together and go on dates.

Mio possesses a vague ability to predict events in the near future. Later in the story, specifically in episode 12, it is revealed that Mio herself is a magical girl. She transforms into her alter ego, Magical Mio, using an orange flip phone as her transformation device, changing into a pink dog-like suit while her hair turns blond. Her partner is a character named Dandy. Because Dandy defeated the enemy on his own during her debut, the specific nature and extent of Magical Mio's own powers remain unclear. Compared to the other magical girls in the series, Mio is notably harsher and more brutal toward her partner's perverted behavior. Her role in the story evolves from Nao's ordinary little sister to an active magical combatant, though her primary motivations continue to revolve around her brother's romantic life and her friendships, particularly with Ink.