Medusa (Shingeki No Bahamut)'s Magical Girl Official Alternate Costume was first introduced in Shingeki No Bahamut from Magic Admiral Lovely★ Monica Sweets! Event (魔法提督ラブリー★モニカsweets!) from 2015/09/16 to 2015/09/24.
It was later re-released on February 14th, 2018 as her Valentine's outfit in Granblue Fantasy.