Lucy is a 30-year-old Mandrake, who grew at the mouth of a cave behind Seinagi Private High School. She was picked by Taiga Kuzumi after he cried at another mandrake's death. She follows him around and helps on his adventures.
Normally, the magic plates prevent the students from seeing the mandrake illusions, but Taiga's fake plate doesn't provide the same protection, and he sees her as a fully nude 6" tall green-haired girl.