Also known as: おふくロイド, あるドロイド
The titular protagonist of The Story of a Droid, a story set in Kato Takuji's Mechanical Buddy Universe.
A masterless android who found an abandoned child and decided to raise him.
To do that, it starts wearing a female 'cyber-skin' and becoming the boy's mother, turning 'it' into a 'she'.
Rainy is her aforementioned adoptive son.
She is given the name "Blau" in the serialized manga "Mechanical Buddy Universe 1.0".