A dispassionate, withdrawn assassin, Golden Darkness is hired by one of Lala's arranged suitors, Lacospo (ラコスポ, Rakosupo?) to kill Rito, until she breaks the contract, noting the true nature behind her target. Golden Darkness is currently staying on Earth, roaming around the city streets and Sainan High, with a motivation to continue her duty to assassinate Rito, although she has yet to accomplish this (hinting she only said that as an excuse to stay on Earth). Commonly referred as "Yami-chan", she spends her time reading books and magazines, while eating taiyaki (it is the only thing she eats on Earth since it is the first food given by Rito and perhaps to show her feelings for him, prior to spending a night at the Yuuki residence for a sukiyaki dinner)
By her planet's calculations, she is 24 years-old
Like Lala, Golden Darkness' physical abilities are exponentially stronger than a human's. She carries a unique ability to turn her body parts into various objects, ranging from swords to dragon heads, however by doing so she riskes her health as stated by Mikado. She states she hates "ecchi" people, and does not hesitate to assault a person who looks at her in an obscene way. Golden Darkness has also shown signs of liking Rito one such is when Nana and Momo invites Rito and the others to their game world, she appears to not want Rito to tell his feeling to Lala and she got jealous of Rito getting attention from the girls during the Sainan Fireworks Festival.