Kokonoe Rin

Background
Rin Kokonoe is the central character and main protagonist in the manga Kodomo no Jikan by Kaworu Watashiya.

Relationships
In canon:

Aki Kokonoe: Rin's late mother, and caretaker for Reiji. She died of cancer while Rin was still in kindergarten, and her death affected Rin deeply. She blamed herself for her mother's death, due to her failure to fold one thousand paper cranes. For over a year after Aki's death, Rin barely spoke, and never smiled.

Reiji Kokonoe: Aki's cousin. He adopts Rin after Aki's death and raises her on his own. He was in a relationship with Aki and it is heavily implied he had designs on Rin once she came of age. Prior to moving in with Aki, Reiji lived with his abusive father and timid mother. It is implied he may have had something to do with their deaths, and he continues to have anger issues well into adulthood.