Horimiya fleshed out its co-protagonists incredibly well. Many side characters, however, got maybe one episode focused on them before being pushed into the background and used as comic relief. And in one case, the anime missed a huge opportunity to dig far deeper into one young character’s particularly dark story.
Prior to Honoka Sawada’s appearance in Horimiya, the anime focused mainly on Kyoko Hori, Izumi Miyamura and a small bit on Toru Ishikawa. After Hori and Miyamura started dating, Sawada appeared to declare her love for Hori and disdain for Miyamura. She went so far as to stalk him and comically argue with him. However, it's revealed that she had a brother around Miyamura’s age who looked oddly similar to him, but he passed away the year before.
Unfortunately, every scene involving Sawada afterward was significantly lighter and her uniquely dark backstory was never discussed again. In fact, she was only on-screen throughout all of Horimiya for about 14 minutes. Her role became mostly comic relief and to help showcase Miyamura in an older brother-like form, which was never expanded on. When it came to Sawada, developments appeared to have happened offscreen, which the audience had to accept and move on. Horimiya had a big opportunity to dig deeper into her past and to help viewers understand her relationship with Hori and Miyamura, but it didn't do so.
Whether it was because Miyamura looked similar to her brother, or because he lived physically close to her, or because Miyamura was always around Hori, Sawada saw parts of her brother in Miyamura and became attached to him. Being next-door neighbors, Miyamura provided a safe space for her. After seeing that she was still processing her brother's death and combatting loneliness, he spent time with her and invited her to eat cake with him whenever she wanted.
Miyamura showed his brotherly protectiveness by scaring away some boys who were bothering Sawada. Later at school, he attempted to help her learn to tolerate the good men around them rather than being afraid. This showed growth for Sawada’s character, but the lens focused more on Miyamura when they were on screen. Sawada’s interactions with the obnoxiously loud Shu Iura did allow the audience to see her slowly overcome her fear, but again, it's framed in a comedic way.
Sawada’s unique relationship with Miyamura was incredibly touching and helped balance her intense crush on Hori, the latter of which was the catalyst for her appearance in Horimiya. However, the show never really explains why she felt so strongly for Hori, nor how she found herself in that position. Instead, she became a cheerleader-type character, constantly rooting for Hori.
Horimiya spent an incredible amount of time on Miyamura and Hori but also designated time for -- usually one episode -- for each secondary character. However, none of the others came close to Sawada’s level of potential depth or her dark backstory, yet she almost appeared like a flash of lightning. Even Hori and Miyamura’s playful antics got more screen time than Sawada herself.
The show could’ve looked into Sawada’s grieving process, her brother’s cause of death, or even what caused her to fear men so much. Her character could’ve been fleshed out in a way that didn't make her so dependent on either of the main protagonists. With such tantalizing hints, Honoka Sawada's story surely could've stood on its own like the other secondary characters, possibly even having an effect as powerful as Miyamura’s backstory.