BL isn’t even a genre so much as it is a marketing group.
In Japan manga that focuses on mxm relationships is generally broken into two main groups - BL and geicomi - in order for the various comics to be more marketable.
Geicomi is what is often mistakenly called “bara” by westerners. This is usually with more muscular men, lots of hardcore sex, bdsm, abuse and little to no story, and is marketed to middle-aged adult gay men as erotica. There’s very little censoring of sex apart from maybe a small bar across the genitals to comply with Japanese obscenity laws.
BL is what is mistakenly called “yaoi” by westerners. This is usually with guys that tend to fall more in line with traditional east-asian beauty standards (bishounen and ikemen). If there is sex (and there very often isn’t), it will be more softcore and will be part of a story. Oftentimes the genitals arent drawn at all. There’s usually more romance and an actual plot. This is usually marketed to a younger audience - late teenage and young adult women. Why women? Because romance as a genre is very much seen as a ‘girl’s thing’ in Japan, so regardless of if you have a m/f, f/f or m/m couple, if there’s a lot of focus on the romantic aspects of the couple rather than the sex, then it will be seen as “for women”. However, while BL is mainly marketed toward women due to
the expectation that romance is a “girl’s thing”, depending on the
series in question, up to half of all BL readers are male.
There are some crossover groups nowadays, and the two markets are converging more and more, but it’s still quite binary like this.
In Japan, “Yaoi” originally refers to a specific subset of anime
parody doujinshi that satirizes the “no homo” male-male bonding of
earlier (usually) shounen series by portraying it as romantic or sexual.
(x) “Yaoi” referring to solely to R-18 pwp mxm interactions is a western fandom thing and is a misnomer.
It’s interesting that you mention Yasuko Sakata and Akiko Hatsu, as
they were both women that were part of the post year 24 group. Now, the
Year 24 group was a group of women mangaka in the 60s and 70s who
pioneered what later became known as yuri and BL. Originally, their work
was just labeled as “shoujo manga” (meaning girl comics), and they
revolutionalized the genre by addressing LGBT+ gender and sexuality
issues at a time when homosexuality was only just starting to be
decriminalized in much of the world. The creator of one of the first
yuri shoujo manga was a woman named Ryoko Yamagishi.
Year 24
refers to their birth year (1949/showa 24), so the post Year 24 group
were women who were part of this revolutionary group but born after
1949.
With regard to the coining of the term “yaoi” - the
original phrase 「ヤマなし、オチなし、意味なし」refers not to sex, specifically, but to
something that was plotless or pointless, and was originally spoken by
Osamu Tezuka to refer to poor quality manga. This definition of yaoi
(meaning plotless, and referring to her manga as a form of
self-deprecation) is confirmed by Hatsu Akiko herself, and that yaoi itself refers to stuff intended to be a satirization or parody. (x)
This idea of her comic being “plotless” was in comparison with her own
more serious comics, and in comparison with the other members of the
Year 24 group who wrote mainly Bildungsroman genre fiction in
their shounen-ai/tanbi comics that generally requires a background in
literature, culture and history to be able to understand, and thus were very plot-heavy.
Fujoshi means you’re a woman that’s a fan of any kind of mlm fiction,
which can include, but isn’t limited to, yaoi doujinshi, professionally
published BL, geicomi, slash, original novels, and even just if you ship
two male characters from a piece of media who aren’t together
canonically. Having it translated literally as “rotten woman” is what I would consider a mistranslation, as the english word “rotten” has some implications that do not exist in Japanese. Fujoshi is a pun on the word “婦女子” (also read ‘fujoshi’) - which means
“grown/respectable women” - where the “fu” character for “wife” is replaced with the
“fu” character for “fermented/ruined/decay”. It was originally coined by cis straight men as a misogynistic insult,
on 2channel, to deride any woman that created/liked slash, mxm pairings
or even just solo gay characters, and had to be reclaimed, as it implied
that women who had any mxm pairings were ruined for life/unmarriable
and brought decay and ‘destroyed’ the canon material of ‘their’
(male-marketed) series. This is why it uses the ‘fu’ character for
ruin/decay that replaces the ‘fu’ character for ‘wife’ in fujoshi
(fujoshi using the wife character means a respectable woman, fujoshi is a
homophonous pun). It was a way to drive out mxm slash creators out of
what they deemed ‘their’ turf (male-marketed media) by shaming women.
Fujoshi has, thankfully, long been reclaimed, and is used across
multiple eastern fandoms as the word for a female fan of mxm media. It
was translated into English by Japanese speakers specifically for the
purpose of giving slash fans from other cultures words to describe
themselves, and was never intended to be used as an insult again.
Fun fact! :The original term for fujoshi was “yurizoku” (lily tribe), which came
from a gay men’s magazine column (“yurizoku no heya” / “Lily Tribe’s
room”) in the 70s/80s and referred to their female readers. (originally
published in the November 1976 edition of “Barazoku”) Because so many of
these female readers were lesbian or bisexual, the shortened term
“yuri” eventually came to mean fxf relationships in manga and novels.
Fudanshi means you’re a man that’s a fan of mlm fiction and/or mlm ships (though because geicomi is marketed to men and expected to appeal to mlm, it generally doesn’t count unless it’s a crossover-type manga as mentioned above).
I hope that I addressed everything there.
