Sailor Moon is often heralded as a landmark anime for LGBTQIA+ representation. Most of the praise focuses on Sailor Uranus and Neptune, but there are other queer characters in the anime. Zoisite and Kunzite are villains from the first arc and are in a same-sex romance. Fish-Eye is a highly effeminate gay man. Fiore's relationship with Mamoru is undeniably homoerotic. The Sailor Starlights can be read as either crossdressing queer women or as genderfluid.
However, one prominent queer character who is often overlooked is Sailor Moon herself. Usagi Tsukino's bisexuality is expressed throughout Naoko Takeuchi's original manga, the 1990s anime adaptation and Sailor Moon Crystal.
The Central Love Story of Sailor Moon
Some fans might ignore that Usagi is bisexual because she ends up marrying and having a child with Mamoru. Many people have a knee-jerk reaction where they cast doubt on a person's sexuality if they enter a hetero-normative relationship.
Usagi does fantasize about men -- before Mamoru, Usagi flirted with Motoki Furuhata, the boy who works at the Crown Game Center. She also has a relationship with Seiya, who she believes to be a male celebrity at the time of their initial relationship. However, while Usagi is shocked in the anime that Seiya turns out to be a woman, her treatment of her doesn't overtly change. In addition, Seiya's relationship is mostly one-sided, since Usagi still is deeply in love with Mamoru.
One overtly queer relationship Usagi has is with Haruka Tenoh, also known as Sailor Uranus. Haruka initiates the flirting with Usagi and Usagi ultimately remains with Mamoru, but it's undeniable that Usagi feels an incredible attraction to Haruka. Haruka kisses Usagi right on the lips, and Usagi really seems to love it.
The Self-Doubt of Sailor Moon in the Anime
Haruka and Usagi kissing was skipped over in the '90s anime. Despite moments indicating that Usagi is attracted to Haruka in the 90s anime, she never gets as intimate, despite multiple times flirting with Haruka and, upon initial meeting, being struck by her beauty -- though both Minako and Usagi at the time thought Haruka was a man.
Then there is the incident during episode 178 of Sailor Stars, where a girl hands Usagi a love letter with the intention of passing it on to Yaten, one of the Sailor Starlights. Usagi initially doesn't understand the girl's intention, believing the girl is giving her a love letter. Trying to let her off gently, Usagi says "Don't cry. You can't be my love, but we can still be friends. Besides, it's better to be in love with a boy." Many fans might cite this '90s anime-exclusive moment as proof Usagi is heterosexual.
However, even the '90s anime still has Usagi showing attraction to other women, especially Haruka. She also admires plenty of women throughout the series in one-off episodes, calling ladies "pretty" and "beautiful" on a regular basis; while this doesn't necessarily indicate sexual or romantic attraction, in the context of her manga characterization and the Haruka flirtations, it contributes to the bisexual reading of her characterization. The inconsistent approach to Usagi's sexuality over the different seasons could be attributed to the anime changing directors multiple times.
It isn't uncommon for bisexual people, especially during puberty, to be in denial about their sexuality. On top of that, most bisexual people don't have precisely equal interest in same and different genders, with many having a preference for one or another. The '90s anime version of Usagi is more attracted to boys than girls, but as seen by her continuous flirting and eagerness to be held by Haruka, she's not entirely straight either.
The Unrestrained Bisexuality in the Manga and Crystal
While the '90s anime version of Sailor Moon restrains Usagi's bisexuality, the manga and Sailor Moon Crystal put it all on display. In both the manga and Crystal, Usagi starts blushing around every single female character she encounters. The manga illustrates her heart racing when she meets pretty girls. She's still as boy-crazy as in the '90s anime, but she expresses her attraction toward every single one of her friends, going out of her way to meet Rei and Makoto just because of how pretty she thinks they are. It's also worth noting that Usagi is more overtly sexual in the manga than the '90s anime.
While Usagi is intimate with both Haruka and Seiya in the '90s anime, these relationships are presented far more intimately in the manga. The manga version of Usagi spends more time in private with both characters. Some of their interactions are easily interpreted as dates, especially with Seiya. While Seiya physically transforms into a male body in the anime, the manga iteration of Seiya is a cis woman who disguises herself as male in traditionally masculine clothing. Sexuality and gender is never an issue when it comes to Usagi and Seiya's relationship, and Usagi only calls it off because of her commitments to Mamoru.
Usagi remains faithful and loyal ultimately to Mamoru, despite her multiple same-sex crushes. She remains attracted to multiple women over the years, but this never changes her loyalty to her true love. None of this invalidates her sexuality; bisexual people don't simply stop being bisexual once they enter an opposite sex romance. It does not matter that Usagi doesn't end up dating Rei Hino or run off into space with Seiya. The fact she expressed attraction to them and found them sexually alluring is enough to validate her sexuality. Usagi Tsukino remains one of anime and manga's greatest bi-cons.