Working on it.
I guess you may call it a harem, but in ancient Japan (which Naruto is heavily based on) there was pretty much a main wife, and secondary ones. Concubines were also there, but it depended on circumstances. I think you still remember those videos I posted with explanations on ancient Japanese cultural customs in this thread.
But it's not exactly what I would call modern harem, and also not exactly classical (which was pretty much a complex social structure, where many 'concubines' in fact never slept with the head of that harem, and it was more of a specific type of court).
https://www.youtube.com/c/Linfamy/videos - Linfamy is a phenomenal YouTuber who shows lots of interesting facts about ancient/medieval Japanese customs, in case you don't know about him.
But this explains why they wanted more wives, and why it was acceptable.
The Naruto world is so weird. They become adults so young because of their responsibilities, but they still aren't mature, emotionally, mentally, or physically. I like the Anko shipping, and I'll admit that I don't know much about the character other than all that crap with Orochimaru, but I have to wonder what she sees in someone so young. Assuming he removes her seal like in the original, I would have expected her interest in him to really peak then. While I'm not against what's happening now, and it certainly feels more organic than in the original version, it still feels a bit rushed. Maybe if there was a side chapter from her perspective, that would help.
This is how it was in medieval times, including Japan. The concept of 'children' wasn't a thing really as mentioned before.
And yes, 12-13 years old marriages, and
pregnancies were a thing. The concept of lolicon didn't exist back then. Shotacon also wasn't a thing, if society allowed it that is (Ancient Rome, Ancient Greece).
Here you may find an article on 'there was no childhood in medieval times' which IMO applies to Naruto world reasonably well. At least by shinobi standards. Children were pretty much 'mini adults' and there was also an open belief that some of them are born sinful, and they need to 'grow' out of it. Being a child in medieval times wasn't easy, in their already really hard lives.
Far as I know, that's how it happened in the world before modernity. I am open to being wrong, however. Gandhi was married at 13, for example, though that's not Japan.
This is how it was pretty much everywhere. Japan wasn't an exception.
Also, a reminder seducing strategies in Japan by our standards could be REALLY creepy, but it worked for their society.
And the whole romance ritual angle.
Honestly, from what I can gleam from reading her bio, she's normally a Hunter-Nin that specializes in ranged combat. Her being Orochimaru's apprentice indicates a scientific background and she is deathly loyal to Konoha.
We don't know exactly why Orochimaru picked her. Her being talented in scientific field does make sense, but shinobi in the end don't care as much about it as being efficient in combat. Making her scientifically smart makes sense, but it's not a requirement, as there isn't any evidence to prove it.
Given that it's culturally acceptable for people to get married so young (though I don't think it's common) and that Daisuke doesn't act like a typical twelve year old and you've got the perfect situation for attraction to bloom.
Naruto also feels at times really modern, so their culture being a mix of modern, and ancient Japan wouldn't be completely off. But in the end, they do have 'you are already adult at the age of 12' with genin, so those may be happening more often than we would like to think about.
In my opinion, that's the kind of thing that would drive a woman to propose.
It's the moment of the biggest betrayal of her life, and also a permanent
reminder of it. Someone removing it is a big deal, and honestly with how mercenary whole dating/seducing/marriages could be in Japan, Anko instantly claiming someone who would do it is in character IMO.
Given Anko's past, she greatly appreciates someone that is reigning their physical interest in so they can develop mental and emotional bonds (after all, she's been doing that for years). That, and he's very nice to her and helps her when he can. The gate was opened, per se, when he helped her save face in front of the Hokage so she didn't wind up in extremely hot water.
What I also appreciated in your previous story (and possibly this one as well) that you never followed with 'turbo-nympho-slut' fanon that was there, as there is zero direct evidence to it. Yes, she liked to wear provocative clothes, but in the end she was a kunoichi, and it was a very obvious distraction tactic. And it worked.
Yes, it may be possible, as there is also no evidence against it, but it's annoying with how shallow some people try to make Anko.
But going with her simply dealing with toxic relationships makes sense, and it may explain some of her actions.
So, when's the Hokage going to start trying to set our MC up with wives? He's loyal to people, not the village, so the best way to secure he stays in the village would be to tie him down to it with a harem. I'm surprised he hasn't started doing that yet, unless he's secretly hoping Anko can do that.
I think when he reaches chuunin rank would make sense, as it's the first rank where people in this world feel shinobi start being leaders, aka responsible people. More or less.
If we're just going with English being a thing which already exists, but isn't commonly spoken I totally understand. Fitting in completely unexpected elements on a world-building level can be scary.
Making English a thing is a pretty big world-building change, although maybe there was in the past civilization who used it, and shinobi hijacked it for their own specific uses.
Or Daisuke and that guy roaming around aren't the first English speakers that showed up in Elemental Nations, which also makes sense.
Also, we don't know what is there outside of Elemental Nations. In one of the movies
this showed up, but I think in the previous story it was pretty much Elemental Nations only and summon clans.
So if you go with this Fulcon, I think you may sit on it, and think a bit on worldbuilding perspective more, as it is a pretty big change, that should affect past of this realm.
Onto the Anko relationship bit. I want to just point out that Anko is very forward and suggestive even with people she isn't actively considering courting. We all remember the scene from Naruto canon where she heard little Naruto bragging, cut his cheek with a thrown kunai, proceeded to lick it clean, and finally comment that she loves braggarts as they tend to bleed the most right?
Personally, I don't take that scene as her being suggestive in any way unless it's more for the people around in that scene (which would make sense). Creepy - oh yes. But she first, and foremost wanted to scare him off, and she pulled it off.
My point? She can very easily have a friend whom she flirts with well before actually considering anything serious. She's no stranger to wandering eyes, and I'm pretty sure the literal mesh catsuit was chosen to encourage it. I'm not making some creepy easy consent joke. Just positing why one could not be offended by wandering eyes without having seriously started a relationship. It's expected.
Distraction tactic. But yes, she also may simply like to show off, and flirting is part of it. Unfortunately, Anko's characterization in the canon is pretty limited, so we work with limited material really.
I totally agree with Anko not being included in the coming mission. An extra Jonin and his team of combat specialists is good backup. That and yet another extra Jonin? Having to come up with justifications for why fights don't just immediately end without just adding more to fight that turns to a messy scrawl. What the bloody hell shows up to fight that, while maintaining tension, without being a damned S ranker? And if it would be an S ranker we start having to escalate the story to having the attention of S rankers too soon.
There is no need to include Anko, and most likely Hiruzen realizes it as well. Teams are already stacked there, and Anko may be always used for something else in Hokage's eyes.