Murasame Shizu

The ghost of a girl who died in the old abandoned school building 400 years ago, Oshizu is sincere, kind, and very curious about the modern world, but has a severe fear of dogs, likened to Haruna Sairenji's level of fear to the supernatural. When frightened, she can emit blasts of mental stress, blowing apart various objects and surroundings, but is also capable of manipulating others through sheer willpower. Since her meeting with Rito and the others, she begins exploring the world outside the old school building. Oshizu is aware of Haruna's crush on Rito by her ability to sense feelings while possessing another person and becomes very supportive towards cheering Haruna into confessing her feelings to him.

Oshizu "returns" to the living, after Ryoko Mikado creates a prosthetic body for her to inhabit, built with biological qualities (looking and feeling like an actual, human body). However, she occasionally "disconnects" during brief moments of excitement. She currently works as a nurse for Ryouko. In the first anime, Oshizu is not given a new body and her presence is limited, while she has her body as she does in the manga for the OVA releases and the new anime.

She appeared in Mayoi Neko Overrun! as a customer (with Haruna)

Ryoko Mikado
Mikado was the one created her artificial body for her to walk among others. Oshizu now lives with her and works at her clinic as her nurse (she can be clumsy though). Oshizu can be very obedient to her, like when Mikado asked Rito to rub sun tanned lotion on her she used her powers to force him to do it.

Haruna Sairenji
Originally Haruna had great fear of ghosts and anything supernatural, but while becoming closer to Oshizu, her fear seems to have lightened (although she still shows fear of it). Oshizu knows about Haruna's feelings toward Rito and often supports and encourages her (sometimes using her powers) to confess to Rito how she feels and not let Lala get in the way.

Rito Yuuki
Rito is one of her closest friends she has. She tries to get him and Haruna together, even if it means possesing Haruna's body. In To Love-Ru Darkness she is shown to have some interest in Rito, but it's unknown if she also having feelings for him. Her attempts to use her psychic powers, as well as her psychic panics, often cause trouble for Rito, including causing Rito's latest love confession for Haruna to fail at the end of To Love-Ru.

Mea Kurosaki
While trying to find out more about Mea and her master Nemesis, Oshizu took possession of her to see if she can find anything important inside her mind. While inside, she saw Mea's desire to have Rito lick her. More importantly, she saw a memory of Mea fighting a group of dangeroud aliens demanding to know where Yami is, and also a moment when Mea is talking to Nemesis, but Oshizu was unable to see her.

Oshizu discovered that deep within Mea's mind is a darkness so deep that it nearly consumed her entirely had she not escaped in time. Frightend by what she saw ,Oshizu has been highly mistrustful of Mea ever since.