Ren Elsie Jewelria

Ren Elise Jewelria is an childhood friend of Lala and the boy version of Run Elise Jewelria. As Ren and Run are royalty from planet Memorze, they can change gender in mind and body upon triggering a specific stimulus. In their case, a sneeze. Ren likes Lala, while Run likes Rito. Ren hates Rito because Lala likes him, while Run hates Lala because Rito likes her. In Chapter 9 of To Love-Ru Darkness, Run and Ren permanently separated into two separate beings after reaching 'adulthood'. His hairstyle is similar to Chaud from the video game series MegaMan Battle Network.

Lala Satalin Deviluke
Ren and Lala have been friends sence childhood, Lala would acasionly force Ren to test out her inventions and make him where dresses, dispite all this he didn't seem to mind in the end because was deeply in love with her (but Run did and it caused her to hate Lala). Lala agread to marry Ren if he becomes a real man although Lala doesn't remember this because of her lack of attension span but Ren still tries any way to win her over.

Rito Yuuki
Ren sees Rito as his rival because of Lala's love for him, so he constanly tries to best Rito on who's more manly, even at completely poinless challenges. Ren once accidently kissed Rito, which caused Ren to despise him even more, but caused his female counterpart to fall in love with Rito, something Ren blames him for.

In To Love-Ru, after Run's introduction, Ren seems to rarely be seen trying to act manly to impress Lala and challenging Rito anymore (it's unknown if he has accepted Rito as Lala's lover or still pursues Lala off-scene). While his relationship with Rito received little development, it would seem that Ren has matured enough to put his competition and animosity behind him, and no longer gives Rito a hard time. Though, needless to say, he still cares enough for Lala that he's still reluctant to acknowledge Rito as a fitting suitor for her. In To Love-Ru, Ren reminded Rito that Lala is a very kind and caring person, and questioned him if he is just keeping her as insurance in case things with Haruna don't work out, something that Rito realizes he should be more considerate about.

Run Elise Jewelria
Run is Ren's female counterpart who's shared the same body since birth until they reached "adulthood", causing the two to permanently split bodies. It was through him that she experienced the kiss he accidently had with Rito, the cause of her love for Rito.

It was seen that Ren and Run are capable of communicating with each other while sharing a single body. They generally took turns with who lived in the shared body, while the other slept. Run eventually became the more prominent personality, and she would sometimes turn back into Ren in situations that are very undesirable for him, sometimes even intentionally when the situation is undesirable for her.

After they became seperate people, they began living together. It's not known in detail what their lives are like together, or how they get along.

Kyouko Kirisaki
Ren doesn't seem as close to Kyouko as Run is, but she is aware of their ability to swap mind and gender through a sneeze. She has helped them from changing when she and Run are performing together, but this is no longer necessary as the two have separate bodies now.

While Kyouko and Ren are likely to have been acquainted to each other through Run, they have never been seen together before.