Great Conqueror 2 : Shogun Game

I’m pretty sure it goes for those too. I mean, clearly that was an issue for him when he played Miyoshi.

It could be an in-game event.

Alternatively, it could be because diplomacy was not attended to.
Uesugi has Chivalrous and he turns against factions with higher prestige levels.
Chōsokabe and Suzuki both have that trait that makes their clans hostile to factions with higher prestige levels.
Takeda still has Expansionist Keener.
And some past feud (gain) statuses probably expired.

I believe it’s an in-game event. At a certain point, your nation leader will have dialogue saying something along the lines of “The surrounding daimyos refuse to let our clan grow and have formed secret alliances against us.” Then, I think you lose something around 100 diplomacy with all nations within diplomatic range. I’m not sure what the exact trigger conditions are though.

The best way to counter this is to plan you diplomacy a head of time. What I did when I played as Mori was get Akamatsu and Ishiki clan on 200 relationship while conquering Yamana, Miura, and Uragami clan. I also didn't max my castle because it might trigger the dialogue saying “The surrounding daimyos refuse to let our clan grow and have formed secret alliances against us.” I built up my forces but not too much so I won't activate the trigger by accident and focus on conquering Shikoku region. Though not sure if this the effectiveness of my conquest but it works.

So that worked out for you, but ngl, you're paying WAY too much respect for that event. I really can't understand why you'd do that with those clans if you're planning to kill the other weaklings in your way. Mori has one of the easiest starting positions in the game in every single conquest. Even with like Lv. 10 units or so and your best guys being like rank 4 or something you should still probably have no issue steamrolling your way through everyone in Armed Unification. Chosokabe and Miyoshi are also no real threat because the AI sucks at naval invasions and everyone gangs up on Miyoshi.

I am just writing this just to correct my previous post about prestige effecting the event in Armed Unification. With a few experiments I have concluded that Prestige has nothing to do when activating the event and has everything to do with how many castles you have which is 20 max, so my previous post about my conquest in Mori clan that one shouldn't max their castles because it might activate the in-game event is worng and shouldn't be followed because it is extremely inefficient. Also when should we be expecting a new update? I really can't wait for the new campaigns and renowned clans stories that are yet to be shown in the game.

Some purple items are repeatedly purchasable/forgeable, some aren't. Not sure this is a 100% rule, but generally items forged or purchased with broken blades are repeatable, items purchased with ban-kin aren't. If the scroll isn't available in the treasure pavilion then I think you have indeed auto-corrected it.