Mecchii debuts in the anime as the seventh demon ally for Setsuna and Mirai. Initially perceived as male and mistakenly called Cool's "Little Brother," her female identity is later confirmed when she remains unaffected by Nekomata's charm ability. During her first appearance, she defeats significant adversaries like Mizuchi, Abaddon, and Fenrir using potent lightning-based attacks. Mecchii remains a consistent presence throughout the series, being one of only two demons returning in the second part alongside Jack Frost.

In the Devil Children games DemiKids Light Version and Dark Version, she is known as Mecci, classified as an Alternate Type demon at level 5. Described as a cute little demon popular as a pet among Dem's kids, her abilities include participating in the combo "Angry Skies" with Thundar and possessing the power "Demon Magnet."

Within Devil Children Fire/Ice Book, specifically Ice Book, Mecchii's portrayal emphasizes pacifism. She is assaulted by an Amanojaku after refusing to fight, causing her distress, and shows fear upon encountering a Devil Child. Relief follows when the Devil Child intervenes with a warning against watching the conflict. After the Devil Child defeats the Amanojaku, Mecchii expresses gratitude by revealing the location of a secret chest within Akuma no Hokora's caverns.