(To the original commenter: This isn't directed at you specifically- this is a question I think a lot of people have asked, so I am just offering my view in general, not trying to call anyone out or start an argument.)
Jun is a big part of it, but I do think there's more to the yuri than that. One of the reasons HxB has always been one of my favorite manga is because its way of handling girls who love girls is so unorthodox. When interviewed, Hayashiya said she doesn't even think about creating "yuri". Since she was young, "yuri and gay have just existed within her like air". To me, that's a pretty good description for how HxB does things. At its core it's not a romance, so it never establishes a romantic mood. At the same time, it portrays lesbian sexual desire through characters like Jun and Hayate, obvious crushes between young women, and a couple who can only be described as life partners (Kaicho and Miyamoto). The shinyuu system is an obvious parallel to marriage. The crushes tend to develop a lot over time, even though it's subtle, and although those crushes aren't the main plot points, they heavily influence the characters' actions. It doesn't get brought into the spotlight, but I've come to love that over the years. Hayashiya incorporates all of this into her stories by treating this love between women as though it's the most normal thing in the world, to the point where we see the kind of slapstick you would normally only see in comedic situations between heterosexual couples. When characters comment "that's gross" when Jun or Hayate say something sexual, imagine Jun and Hayate as guys and tell me that they wouldn't get the exact same response. Having lesbian attraction, both sexual and romantic, be subjected to the same standards as heterosexual attraction is really refreshing, for me at least.
Long story short, I think you're right that HxB isn't exactly yuri. It's just really really gay, and as a lesbian, I love the fact that HxB allows so many girls who like girls to exist outside of a romance setting, because we do exist outside of our relationships. But since Dynasty doesn't really have a tag that can describe that, the closest we can get is the yuri tag. And I think it's really important that the gay aspects of this manga be expressed through that tag, because they are an important part of it.
You pretty much hit the ball on why I enjoy this manga so much. It's not a romance manga, it's an action/comedy manga. The action is top notch + actually funny slapstick humour? not to mention 99% of the characters are hella gay. It's an enjoyable series even without the snippets of romance, but it's definitely the flavourful icing on the cake that makes HxB so wonderful.
Harumi and Yuzu definitely have more chemistry than Yuzu and Mei. Overall this series felt pretty shallow with some crappy drama that left a sour taste in my mouth. It's nice to see a serial series coming to a close though, even if it was pretty mediocre imo.
Damn, lets hope this is the last of the biphobia in this comment thread, I don't want to read any more comments like this. Pure lesbians lmao
No wanting hetero or bi relationships in your yuri story is not really biphobia.
this is last thing im going to say about this, but saying that is what makes you biphobic. people are bisexual irl and their sexuality should be respected even in yuri. Let us enjoy our Korean yuri without your "pure lesbian" rulebook.
Just a question for those who know actual Japan: Is this sort a thing a major crime like it is here in the US? A minor crime? Not actually a crime but certainly grounds for termination? (I'm talking about the teacher/student shenanigans, of course--not the lesbian activity.)
In these stories, the teachers always seem a bit wary, but not afraid-of-landing-in-prison wary.
The way I see it, the purpose of this doujinshi is to show sex with little background story and drama (thats how most of these go). The teachers thoughts about "sex with a minor could land them in jail" are not there because it would cause useless drama that would take extra pages.
If this wasn't a one shot, but a series, then I would be kinda disappointed if there wasn't drama with this subject 9 times out of ten there isn't, but that's just me.