Konjiki no Yami (Golden Darkness)

Golden Darkness (金色の闇 Konjiki no Yami?), mostly referred to by other characters as Yami, is a major character in To Love-Ru and To Love-Ru Darkness. She is a lonely assassin who is initially hired by Lacospo, one of Lala's arranged suitors, to kill Rito Yuuki. But when Lacospo effectively annuls the job, she decides to take her time and, under the pretense of still needing to complete her mission to kill Rito, stays on Earth. As she spends more time on Earth, she builds a very strong relationship with Rito's mature younger sister, Mikan Yuuki and to Rito himself, whom she also develops feelings for.

In To Love-Ru Darkness, Yami becomes central to the main plot. This is because there is a group that wants her to join them as the heartless assassin she once was. Her "sister", Mea Kurosaki (a transformation weapon of the same program that created Yami) and a mysterious figure known as Nemesis, arrive to Earth to take her away and revive the old heartless/murdering self that she once was.