A prisoner who is like the sun, always chatting and laughing. Mahiru treats everybody the same way. Due to her genuine, pure and bubbly nature, she's easy to trick but she always laughs it off. She is a bit of an airhead at times but is kind nonetheless. After the events of Trial 1, Kotoko (referred to as "Kotoko-chan") beat her up badly (due to the fact that Mahiru received the "unforgiven" verdict). She has had one lover total (now deceased).