Are there similar games to this?

[Harem Route]

Basically, character-driven strategies, with diplomacy and waifus
I know ROTK, of course, but couldn't get into it as much as NA. Although I do appreciate the ability to have a harem
Then there is Dynasty Warriors: Empires. Which I love a LOT but would barely call a strategy.
And of course, there's Crusader Kings, which... is a bit too complicated for my taste, but still fits the description.
And then there is Sengoku Rance... but I'm not sure I can talk about it here. Still, kinda fits as well.

Anything else?

[ankhefenra]

There's Total War series, but it doesn't have any story, or so I've heard, so probably not what you're looking for. Oh, and the Civilization series. I haven't played either, so I can't say how smilar they are to NA.
There's also Legend of Cao Cao (made by Koei). It's very old,1999 I think, and an English translation can be found in Kongming's archives. It also got a mobile remake recently. (The music is really great and as the title sais, you play as Cao Cao and his followers, with a historical and a hypothetical path). Otherwise I'm not that familiar with historical strategy games.

And which ROTK did you try? I've only played 10 and I loved it, there you have only one character to play as, but 11 for example is more like NA, where you play the whole "clan". I've heard some say 11 is the best ROTK.

[Delacourt '27]

I think you are on the wrong forum, since NA:SoI doesn't have

Originally posted by Simon.cleric:

Basically, character-driven strategies, with diplomacy and waifus :Ageha:

NA:SoI Ascension has them.

I saw someone give a bad review to ROTK XIII because it's a copy of NA:SoI. If you like NA:SoI Ascension, maybe ROTK XIII is for you, if you haven't try that one.

I don't think there is another series out there that satisfy all of what you asked for.

Total War for strategies and diplomacy.

Some RPGs for character driven strategies, Suikoden series. Waifus, Skyrim/Witcher.

Some other character driven strategies might be Mount and Blade, anything but the original will have story, some even have diplomacy, while others might have waifus, well, maybe wife/husband.

Real Warfare 2: Northern Crusades is Mount and Blade with Total War warfare style.

[fairy]

I'm new to this game but I find it way more complicated than crusader kings, i'm surprised you feel the opposite!

If you've already tried ROTK, try The Last Warlord? it's a three kingdoms game but it's not made by Koei, it looks really interesting

[kokushun]

If you like Chinese history, then Oriental Empires is a game somewhat similar to this: detailed strategy in medieval asian setting. Though, no waifu and almost no characters. And yes, it's China, not Japan.