Miwako Kirigaya in the manga
Miwako Kirigaya is Satoko’s younger half-sister and the daughter of Jubei and Rie. She is proud and competitive, with a strong need for the attention Satoko seems to receive so easily.
Her resentment gradually gives way to support for Satoko’s choice of Shinpei. She helps him understand what Satoko’s farewell letter leaves unsaid, making her an important ally in bringing them back together. The sisters’ bond becomes warmer as Miwako stops treating their futures as a competition.
She can help her sister before becoming free of rivalry.
Miwako has learned to measure attention as something Satoko receives at her expense. The later chapters give her actions that cannot be contained by that first impression.
Chapter references identify the scenes behind each argument. “Our reading” is an interpretation, rather than a statement of the author’s confirmed intent.
A useful act can have mixed motives
Chapters 49–53
Miwako helps Satoko put genuine feelings into the letter meant to break with Shinpei and helps them meet. She later stops Satoko from harming herself. In Chapter 53, she still voices her own competitive interest in becoming the family’s most valued daughter.
Her help does not require a completed transformation into a selfless sister. The rivalry continues, yet she acts at moments when Satoko needs someone. That combination makes the change more credible than an abrupt reversal of personality.
The sisters have been placed inside a contest neither invented. Miwako’s later choices interrupt its expected result: the rival can also be a person whose pain she recognises. She has not solved the family’s hierarchy, but she does something within reach that matters.
