Adachi to Shimamura is a light novel series by Hitoma Iruma with illustrations by Non and has been adapted into both anime and manga. Despite being a yuri romance of the iyashikei genre, one of its protagonists, Shimamura Hougetsu, is surprisingly colder than winter in Hokkaido. Since she is the love interest of the other protagonist, Adachi Sakura, her emotional detachment is often a source of conflict between the two girls.
While it's clear Shimamura enjoys Adachi's company more than her other friends, she also keeps Adachi at arm's length. Even when she reunites with her childhood best friend Tarumi, her aloofness persists when the latter tries to rekindle the emotional closeness they once shared. With two of Shimamura's closest friends pining for her love and affection, it begs the question: "What is going on with Shimamura that she doesn't reciprocate?" While both the anime and manga adaptations provide some explanation for her behavior, the light novels do more to fill in the gaps.
Shimamura Was Burned by The Loss of a Childhood Friend
One relationship that's explored more in-depth in the Adachi to Shimamura light novels is Shimamura's past with Tarumi. In contrast with the 16-year-old Shimamura of the present, her younger self from kindergarten to elementary school was much more energetic, outgoing and carefree. As such, she made friends easily with other kids and was especially fond of Tarumi, who was always a bit shy. They even gave each other cute nicknames in the form of "Taru-chan" and "Shima-chan" as children.
To further drive home how different the younger Shimamura was from her present self, a chapter in Vol. 5 depicts how differently her relationship with Adachi would've been if they'd met as kindergarteners. Since Adachi has been extremely introverted from a young age, Shimamura would've had trouble relating to her. Whereas the younger Adachi would've wanted to monopolize her company, the younger Shimamura would've rejected her in favor of playing with Tarumi and their other classmates. Tarumi would've similarly protested against Adachi stealing Shima-chan away from her.
Shimamura and Tarumi's friendship came to an abrupt end when they went to separate schools for junior high. This proved to be a devastating loss for both girls, which negatively impacted their self-esteem. Shimamura was forced to form new relationships again but found it difficult to relate to her new classmates. After failing to meaningfully connect with them, she eventually gave up. Tarumi started to become depressed, which led to truancy. While the separation was neither girl's fault, it nonetheless informed their future interactions -- and especially Shimamura's future emotional coldness.
Shimamura Is Frequently Invalidated by Her Mother
Compounding Shimamura's negative feelings toward relationships is her highly critical mother. While Shimamura is at least fortunate to have an engaging parent who cares about her future, she also doesn't do so in a validating way. Her mother consistently reminds her of her failures and criticizes her flaws in front of other people, more so than nurturing her daughter's positive traits and rewarding her accomplishments.
Shimamura finds this behavior from her mother hurtful, and every time she asserts her boundaries, her mother ignores her and doubles down on criticisms. She has done this consistently in Adachi's presence, often leaving Shimamura feeling angry and embarrassed. Though Shimamura doesn't wear her anger on her face, she still internalizes it, which yields negative outcomes. The end result is an inability to establish and maintain healthy boundaries, along with a tendency to withdraw from most social situations and keep her relationships surface-level.
Shimamura Is Protecting Herself Against More Hurt
The present-day co-protagonist in Adachi to Shimamura is a high school girl who has completely lost touch with the person she is, thanks to compounding negative experiences with relationships. Despite having an amiable personality that makes her attractive to other girls, Shimamura still doesn't think too highly of herself and struggles to define her self-worth. This problem is only exacerbated by the fact that identity in Japan is largely shaped by the relationships one possesses. An absence of significant relationships in Japan often results in a loss of identity for an individual, which is exactly what happened to Shimamura.
On an individual level, Shimamura is aware she's become emotionally cold as an adolescent, and that her actions are easily perceived as cruel by others. At the same time, she takes comfort in that perception of herself because it shields her from future painful experiences. This cynical mindset also informs how Shimamura connects with her classmates Hino Akira and Nagafuji Taeko, whom she thinks of as superficial friends. She likes both enough to hang out with them, but never gives them the opportunity to get to know her as a real person. When she meets Sancho, Pancho and Delos in her second year of high school, she doubles down on her policy of not letting anyone get too close.
When Shimamura befriends Adachi, she is surprisingly drawn to her but doesn't understand why. To an outside observer, their connection is based on the fact they're both truant students -- which, interestingly, is the view she accepts. Even when it's obvious to her that Adachi loves her as more than a friend, she has a hard time accepting it and rationalizes Adachi's behavior as a symptom of her own neglectful upbringing. As such, she opts to become Adachi's "older sister" and indulges her need for affection in a similar fashion to her own younger sister. It's not until Tarumi comes crashing back into her life -- purely by chance -- that Shimamura is met with a serious reality check.
Adachi to Shimamura's reintroduction of Tarumi puts a lot of cracks in the walls Shimamura built around herself over the years. Not only does she get back the best friend she'd lost, but she's immediately returned to a place of emotional pain rather than excitement. Shimamura's immediate response is to keep her emotional investment in Tarumi at arm's length. This reaction is puzzling to Tarumi, who can't understand why Shimamura isn't as excited about their reunion and is immediately hurt by her emotional coldness. When Shimamura realizes how her cruel behavior is hurting Tarumi, she starts making a concerted effort to change -- though not necessarily in a way that reconnects her with her real self.
