What is the theme in Kitchen by Banana Yoshimoto?

Sex roles is an important theme in the book. One of the most notable facets of the story Kitchen is the calm and subtle treatment that it gives to Eriko's gender. When Mikage first meets Eriko, she is smitten with the beauty that she sees. Her fascination indicates a sexual attraction, but as she explains that she came to understand the word "charm" for the first time, it becomes clear that her attraction is not physical, that it is more like magic. When Yuichi tells her that Eriko is actually his biological father, that she has changed her sex, Mikage expresses some surprise— "I just stared at him in wide-eyed silence. I didn't know what to say" — but she is not overwhelmed, and her surprise soon fades as she becomes involved in a conversation about Yuichi's family history.