Lily is a main character in Kappa Mikey, whose mean spirit grants her the title of an antagonist. She is a physically attractive girl who works as an actress in LilyMu, Japan's most popular show. In the program, her character is a sweet, innocent and benevolent girl, who often portrays the damsel-in-distress and is adored by the audience. In reality, however, Lily's nothing more than a vain, heartless and overindulged girl who puts on a nice act in front of the cameras in order to keep her image. She was the original star of LilyMu (hence the title) until Mikey Simon, the main character, joined the show's cast and was given the starring role. Having lost the spotlight to him, Lily detests Mikey, and torments and horribly insults him at every opportunity she gets.
Facing a nosedive in the ratings for being unoriginal, LilyMu, who was once the most popular show in Japan, was on the verge of being cancelled. In order to save the show, a contest was promoted in order to find a new star that would bring the program back to its former glory. The contest winner was Mikey Simon, a young actor from the USA, who came all the way to Japan and immediately became the center of all the attention from the producer and the fans. Lily, who used to be the main character and was accustomed to being the star, got jealous and started to develop a dislike for him. Mikey, who initially is oblivious to this, develops a crush on her immediately and makes several advances on her, who usually end up in a sound rejection with displays of disgust from Lily. These appear to become less frequent as the series progresses, indicating that he might have be becoming more aware of her bitterness and resent.
Lily appears to be a kogal (Japan's version of a Valley girl), as she is constantly seen wearing a sailor fuku. She is shown to be extremely vain, deceiving, and self-centered, as she worries about looks and appearances more than anything (for example, Lily tries her hardest to keep up with popular fashions in order to stay on lists for best-dressed celebrities, which she manages to stay on). She is also extremely rude, bossy, snobbish, short-tempered, and inconsiderate to others, thinking only of benefiting herself. Even in spite of his unrequited feelings for her, Mikey legitimately sees Lily as a friend, while unbeknownst to him, Lily appears to have not a single trace of fondness for him, relishing every time she sees he risks getting fired and/or send back to the United States. It is sometimes shown that she is callous enough as not to care about his life. The only person that she demonstrates some kind of endearment for is Mitsuki (who actually has a crush on Mikey), fellow actress in LilyMu and also roommate, whom she almost has a sisterly bond. Even so, Lily frequently insults and belittles her, seeing herself as much prettier than her, and often takes advantage of her leniency and innocence. One episode, for example, reveals that Mitsuki once donated one of her kidneys to Lily because she was sick in a hospital for weeks, but she only sees this act of charity as Mitsuki trying a publicity stunt and is unappreciative and not grateful in the slightest.