Based on available information, Mayumi 1st, also known as Mayumi Mahito, is a character from the anime Luv Wave. She is described as Kaoru's girlfriend from the past. Her exact background is closely tied to the story's central mysteries, and providing further details risks spoiling key plot developments. Her role in the narrative revolves around her past relationship with Kaoru, which serves as a significant emotional anchor for the protagonist. Her personality and motivations are not explicitly detailed in the available sources, but her connection to Kaoru is a driving element in the story. Her development is closely linked to the revelations about the past and the events surrounding the Nine Heavens drug. No other specific abilities or notable traits are documented beyond this foundational relationship and her role as a figure from Kaoru's history.