Also known as: 謎の蘭丸X, 森蘭丸, 謎の蘭丸X(Fate)
Avenger-class Servant in Fate/Grand Order introduced in the GUDAGUDA Ryouma Kiki Ippatsu! event. Like Mysterious Heroine X (Fate), she is from the Servant Universe (Fate), specifically Planet Ranmaru. She is a version of Mori Nagayoshi (Fate)'s brother, Mori Ranmaru. She keeps her right eye covered with an Eyepatch, hiding a heterochromatic glowing red eye.
Her gender is listed as unknown, and uses her own name (Ranmaru) as a personal pronoun. She states that whether she is a boy or a girl depends on "her Ranmanium growth cycles".
Character Design: Mika Pikazo
Voice Actress: Machico (Voice Actor)