Sairenji Haruna/Plot

Haruna is a secondary female protagonist next to Lala, but is the center of Rito's feelings, whom he constantly tried to confess to. Rito and Haruna have known each other since pre-school, but never have interacted with each other until after Lala's arrival and have seemingly become closer overtime. It's revealed that Haruna also has feelings for Rito for a long, but had these feelings buried because of her friendship with Lala. However she managed to tell Lala about her feelings for him, which she was surprised at first, but also supports both their love. Since then Lala has distanced herself from Rito to be fair to Haruna.

Haruna has shown to have a great fear of the supernatural, especially of ghosts. However, when the local ghost, Oshizu Murasame, returns to the living, via an artificially-built body from Dr. Mikado, Haruna and Oshizu quickly became good friends with each other. Oshizu learns of Haruna's feelings for Rito, and became very supportive, though not entirely helpful, for Haruna's success.

When Rito told Lala about his feelings towards her and Haruna, Lala tries to bring them together, because if Rito marries Lala, he will become the next king of Deviluke and Earth laws will not apply to him, making polygamy legal for him, so the three of them can be together.

In To Love-Ru Darkness, Lala continues to push Haruna and Rito together, although Haruna is confused for her reason in doing so. Soon, Momo told her about polygamy being a common thing in space, and the possibility that Lala and Haruna can both marry Rito together. Haruna currently doesn't know what to do with this newfound possibility.