I think that family and familial relationships are huge. In Nao’s family, the mother is rarely seen, she’s very absent. Nao’s father, though still physically present, is mentally absent. He no longer lives within the family mindset and seeks various methods of suicide. Though we are shown, through Oliver, that he tried to be a good father to Nao and purchase her panties to prevent anyone else from deriving a sick pleasure from them. I think that Nao realized her father isn’t alright, but does nothing to help him, though she does push him to try not to fail suicide again. Nao, tries to appease her mother and be a good daughter, but whether this is sarcasm or genuine, the result seems mixed. Jiko’s mere presence is enough to elicit real and deep emotions from Nao’s father. Jiko becomes an important part of Nao’s life, inspiring her to find her supapowa. Jiko becomes a nun because of her son’s death. His love of life for all, and her love for him, kept her from giving in a committing suicide.
Ruth’s mother, is no longer with her. Ruth’s father isn’t mentioned. Ruth’s husband Oliver is what brings her to the island, which she hates. Oliver becomes pushed aside and even a bit bullied by Ruth as she journeys through the diary.