Golden Darkness

A dispassionate, withdrawn assassin, Golden Darkness was hired by one of Lala Satalin Deviluke's prospective suitors, Lacospo, to kill Lala's fiancé Rito Yuki. She breaks the contract after noting Rito's true nature. Golden Darkness came to Earth on the Lunatique, a very fast spaceship (it can travel 30 million light-years in 2 hours). Golden Darkness has decided to stay on Earth, where she roams the streets of Sainan Town, purportedly to continue her mission to assassinate Rito, although she has yet to accomplish this despite numerous opportunities, hinting that she says this as an excuse to stay on Earth, which is then confirmed. Commonly referred as "Yami", she spends much of her time reading books and magazines, while eating taiyaki (it is the only thing she eats since it is the first food offered to her by Rito). By her planet's calculations, she is 24 years old, despite having the appearance of a 14-year-old (her Trans ability has slowed her aging process), although this is only mentioned in the anime. She has also a weakness to anything slimy.
Like Lala, Golden Darkness's physical abilities are exponentially stronger than a human's. She states she hates "ecchi" people, and does not hesitate to assault a person who looks at her in an obscene way. She does though hate when people are free of her as shown in the anime as she beats Rito up after being told by Rito that he's free of her. She's capable of spinning people away if she's caught by someone with a strong grip. She has become close to Rito's younger sister Mikan Yuki and seems to keep an eye out for her, evident when she and Mikan switched bodies and the Principal attempted to grope her, prompting Golden Darkness (in Mikan's body) to warn him not to touch Mikan and deliver a savage beating. Though she always says she will kill Rito one day, it is becoming increasingly doubtful that she will ever do it. In fact, she seems to have begun to develop feelings for Rito. Instead of beating him and saying "I hate ecchi people" like she normally does, she blushes when Rito sees her in a swimsuit and states "Don't look at me with those ecchi eyes". This is also proven further when Golden Darkness nearly tells Rito that she wants him to "embrace" her.
In To Love Ru Darkness, after some convincing from Mikan, she enrolls in the Sainan High school and becomes a classmate of the main cast. Mikan is also giving her cooking lessons. Despite her normal stoic appearance, it is obvious that she does care for Rito, and is shown to be developing further feelings for him, although not enough to forgo the occasional beating when he becomes "Ecchi". Her new life may already be in jeopardy when Mea Kurosaki, a fellow classmate, is revealed to be her 'little sister', suggesting that she will have to return to space and fulfill her contract to kill Rito. It is revealed that Golden Darkness's creator is the Sainan High teacher Tearju Lunatique, and that her given name is "Eve". When Golden Darkness' former rival Azenda hires the alien hitman Kuro to kill Rito, she rescues him from Kuro before she confesses her love to him, making her the second female heroine to convey to Rito.
She is based on Eve from Black Cat, as they both look the same and can turn any part of their bodies into a weapon; they are even voiced by the same actress Misato Fukuen in their respective animes. Also, there's a chapter in To Love Ru in which Golden Darkness tries on a black dress similar to the one that Eve wears in the final chapters of Black Cat.
Kentaro Yabuki initially illustrated Black Cat between 2000-2004, then assisted Saki Hasemi with his manga project To Love Ru. They agreed that a character featured in To Love Ru would be based on one of the protagonists in Black Cat, which ended up being Eve. Her character was recognized for being extremely similar to Eve and is currently one of the most popular characters in the series. Fans also debate whether she could have her own series.