The following contains spoilers for Episode 20 of Komi Can't Communicate, "It's Just The School Field Trip," now streaming on Netflix.
Najimi Osana is a prominent non-binary character in Komi Can’t Communicate. Originally assumed to be male by their classmates due to their history of wearing male clothing and using masculine pronouns, since the start of the series, Najimi has demonstrated more gender-fluidity. In this case, they are depicted as possessing both masculine and feminine qualities, but never squarely identifying as one or the other. This not only reflects in their choice of clothing but in their behavior as well.
Despite the fact that Japan is culturally more open to gender-fluidity and queer sexuality than Western European cultures, as a rule-oriented society, Japan is still heteronormative and still has binary gender norms. While Najimi’s friends, classmates and teachers don’t hassle them about clarifying their gender in most situations, when it comes to splitting groups by gender and accessing gendered spaces, this is when they typically run into problems. This was first explored in Episode 7 of Season 1 and is revisited again in Episode 20 of Season 2.
In the Episode 7 story from Season 1, "It's Just The Pool,", Najimi arranged an outing with Shoko Komi and Hitohito Tadano at a water park during summer vacation. They also ran into Ren Yamai and their mutual friends Shigeo Chiarai, Taisei Sonoda and Mono Shinobino, who also arrived at the park independently of Najimi's invitation. When the two groups departed to change into their swimsuits, Najimi originally accompanied the girls to the women's changing room, until asked by Yamai if they were actually a girl. Najimi was then forced to change in a unisex changing area and the question of their gender never came up again.
A similar scenario plays out in Episode 20 of Season 2. In the story "It's Just the School Field Trip," Komi's class goes on a trip to Kyoto with the class spit into groups of three boys and three girls, with no mixing of genders. The groups were decided in a class lottery, and as per the teacher's instructions, each student had to sit together with their assigned groups on the train ride to Kyoto.
With Najimi being classified as genderless, they were not placed in a group, and occupied an entire row of seats by themself. When Tadano -- the class president -- was tasked with counting all the students to ensure no one was missing, they accompanied him on this task as the class vice president since they had nothing else to do.
On their first day in Kyoto, the students are not strictly assigned to their groups as they follow their tour guide, Ryoko Tenjoin, to various historical sites throughout the city. During this time, Najimi is able to mingle with their classmates without any issue. It's not until the class goes to their first hotel for the night that Najimi experiences their second problem with placement when the groups are once again split by gender.
Since the class is staying at a traditional Japanese hotel, none of the students are given individual rooms and are instead given communal lodging. This results in splitting the class into two groups with boys occupying one room and all girls occupying another. Since Najimi is once again left without a group as the only gender-fluid student, they choose to sleep in the girl's room. This results in Yamai once again asking if they are in fact a girl, and if they belong in their group. Najimi doesn't answer Yamai's question, but they are nonetheless uncomfortable with having their gender questioned. Najimi's gendered issues don't end there.
When the students are given their time slots for using the hotel's public bath, the baths are once again split by gender. Once again, Najimi is not permitted to bathe with their classmates, and is instead given a separate time slot and a private bathroom to bathe in. Between not being assigned to a group and not being permitted to bathe with their classmates, as well as having their gender questioned when deciding where to sleep, Najimi is shown to not be immune to the systemic prejudices that exist against transgender and non-binary people. Despite being immensely popular with other students, they still get excluded from certain spaces and certain activities as a result of not conforming to a single gender.