Tearju Lunatique

Tearju Lunatique is Yami (Golden Darkness) and Mea Kurosaki's creator, as she used her own cells in order to create Yami but didn't do the same for Mea. She is a genius in Universe Biotechnology and has been since she was a teenager. She takes the role of a klutzy (and beautiful) classroom teacher at Rito's school in the later chapters of Darkness. Tearju is aware of Yami at school and tries to get close to her like before.

She is based on a character with the same name and appearance from Kentaro Yabuki's previous manga Black Cat. In that series, Tearju was also a scientist who created Eve (whom Golden Darkness was based on).

Golden Darkness (Yami)
Tearju is Yami's (originely named her Eve) creator and DNA origin, before Yami's life as assassin Tearju treated her like a little sister who was always happy and child like. She would always look up to Tearju, even now calling her one of the smartests beings there is and going as far to eat badly made food she cooked. Tearju planned on escaping the origanization with Yami but was unable to thus forcing to leave her behind with the people who forced her to become he ultimate weapon.

After their incounter for a long time, Yami states that she doesn't blame her and says that she's glade that Tearju is ok. right now she hopes in to becoming closer to Yami like before but she acasionnaly avoids Tearju unless the situation called for.

Rito Yuuki
Tearju became Rito's homeroom teacher in To Love-Ru Darkness. She sees Rito as a close friend of Yami's and she trusts him and understands that he is a very kind person, and even points out that it's like him to notice that something is troubling someone.

Mea Kurosaki
Mea is another transformation weapon created by Tearju. She sees Tearju as a "barrier" for Yami to becoming the cold assassin she once was and wants her out of the way for that. However, since Mea is sort of Yami's sister, Tearju considers Mea to be a sister to her as well, and hopes that Mea follows Yami's example by embracing her emotions and bonds, to which Mea rebuffs under her conviction that she is a weapon.

After Mea has reconciled with Nana, it is unknown what Mea now feels towards Tearju.

Ryoko Mikado
Tearju and Mikado have been friends since they were in school together. They went their seperate ways some time before Tearju was recruited into the suspicious organization where she would eventually create Eve (Golden Darkness).

In To Love-Ru Darkness, Mikado eventually reunited with Tearju to tell her how Eve is doing on Earth. It was because of Mikado that Tearju came to Earth and became the homeroom teacher for Rito's class.

Nemesis
Tearju seems to know a few things about Nemesis and the organization that created her but doesn't seem to know her in person, but Nemesis knows her quite well and said that Tearju is the "barrier" to Yami from returning to a cold heartless assassin.