Death
Death is the primary theme in Kitchen. It separates Mikage and Yuichi from their beloved family members, but at the same time, it is the force that brings the two together. Having lost her grandmother, Mikage is so lost and depressed that she cannot complete the simplest tasks. She gets better when Yuichi and his mother take care of her. Similarly, when Eriko dies and Yuichi falls into depression, Mikage, knowing the feeling of loss all too well, nurtures him and gives him a reason to go on. Both talk about death following them and making them orphans, which increases their bond. Mikage is aware that everything around her, including herself, is only temporary; she appreciates death for giving her the feeling that she is alive.
Gender
The theme of gender is essential to the story because it is the transsexuals who bring Mikage and Yuichi together. Combining traits from both genders and having experience as a man as well as a woman, Eriko invites Mikage over to her place; eventually, she sees the romantic potential of Mikage's relationship with Yuichi. In the end, Chika gives Mikage Yuichi's address and phone number, telling her that she is worried about him. She also forces Mikage to acknowledge that both of them are in love. Without Eriko and Chika, therefore, the two young protagonists would not have found their soulmate in each other.
Moreover, Mikage never judges the trans women in her life but rather is stunned by their beauty and personality. However, Eriko's death shows that there is still a long road for them to achieve equality and respect, particularly in Japan.
Friendship
Though death is the reason for Mikage and Yuichi's grief, friendship and nurturing is the key to overcoming their depression. Both Eriko and Yuichi nurture Mikage after her grandmother's death, pulling her out from the deep hole of depression. Similarly, Mikage nurtures Yuichi after the death of his mother. She has been taught by Eriko that independence has its limitations: just like plants will die without nurturing, people can perish without friendship. The path to achieving happiness is, therefore, a thin line between independence and being too close.
Home
Mikage's favorite thing is the kitchen, which can be seen as a microcosm of the home itself. She feels comfortable there, and when her life with her grandmother abruptly ends due to her death, Mikage is bereft of her kitchen and her home. Yuichi and Eriko offer her a new home and a new family, and even though they are not blood relatives, they fulfill Mikage's needs. The kitchen is the first room in their apartment that she inspects, and she immediately falls in love with it; the kitchen is also where Eriko asks Mikage to stay. Even though Mikage leaves the Tanabe residence to start her own "home," she still has connections to Yuichi. Home is something that Mikage desperately wants and something that might look different at different stages of her life.
Memory and Nostalgia
Mikage is constantly indulging in memories, whether she conjures them up on her own or a sensory experience throws her back into one. She even thinks about thinking about the past, wondering if in the future she will look back nostalgically on her time with the Tanabes. Memory functions as a way for her to keep those who have passed alive in her heart, to forge connections with those with whom she shares the memory, to provide meaning to her life, and to understand who she is and how she has grown. Nostalgia can sometimes be problematic if one wears rose-colored glasses, but all in all, Mikage's engagement with her past seems healthy because she is still invested in her present and her future.
Food
Food is not just sustenance in this novel; rather, it is something that brings people together, something that evokes memory and sentiment, and something that acts as a way for one person—the cook—to show that they care for another. The creation of food is one of the most basic human rituals, and it is one that Mikage enjoys for numerous reasons. Food permeates the novel: it is present at important moments, factors into significant memories and conversations, and is a part of the central character's core characteristics.
Growing Up
The novel only covers a few months or so, but Mikage and Yuichi do a lot of growing up in this time. Mikage, in particular, has to decide who her family is, where her home is, how she is going to deal with the numerous deaths that have happened to those she loved, and what her role in Yuichi's life is going to be. These are all heavy things for a young person to figure out, and Mikage still has the more quotidian concerns of getting a job, dealing with angry women who think she's stealing their boyfriend, etc. Mikage has her dark moments and thoughts that life is too hard, but she learns to embrace the world for what it is, both in its sorrows and triumphs.
