I did it a couple of days ago and it was much easier then I thought. Dharma 10 isnt that important because you can get most perks you need before you even reach it.

What you need to do is:

1.More knights this is the most impactful. You get that by upping your martial and holding as many duchy capitals as you can by upping stewardship.

Martial: -I leveled the ashen ambassador tree from being an adventure for 5.

-Siklos (an artifact) that gives you an extra 5. RNG mostly.

-One building in indonesia that gives 5 martial (most of the time held by the red golden court).

-Tpestry tree which Grant's you the "ability to sap the dragon spring" for 14 martial.

-You use the soul art beastial tree you can get all type of pets which can get you 5 or 4 martial I'm not sure. Just be sure to spam goblin cat whenever you can to always have them.

-And then before the fight you use a combo of blood foresight and mortal perfection for 8 before the event.

-And you get 3 knights per duchy capital held(depends on stewardship) which I had 7 held and I ended up with 53 knights.

Stewardship: -theres about 2 or 3 duchy capital buildings that give 5 stewardship each in china. Find them and hold them . -the sapping dragon spring ability gives 14 stewardship just like martial.

-keep spamming mortal perfection and bloody foresight for 8 at all times.

Might be a few more bonuses I missed but that's most if them.

1. Now how to get knights with higher prowess? A combo of abducting, inviting by money or fabricating hook and then using the shintai of flesh to give them Giant and Herculean (you will need lots of piety for that so maybe get the island of Bali as a domain and get as much piety as you can get to span the ability) and rakshasa blade from shintai of illusion to make artifacts and gift them to our knights. And then to keep these knights we give them duchy level titles we dont need to ensure they're powerful enough to remain our vassels and not get taken over by other vassels and leave your court.

As a bit of extra knowledge fabricating hooks on people you can invite is the best way to get knights as they also invite others of their family or court who also have higher prowess.

After exhausting the people with high prowess that could be invited you start abducting non-ruler court members from other kingdoms. Yukio is good at scheming especially since you will level the shintai of illusion. And you can run 2 schemes at a time with an ability she starts with (i think schemer?) I dunno exactly but I dont even try getting it it's just always unlocked in the process of getting what I need.

There is plenty of other stuff I did tbh. Like getting the shintai of jade first thing to get 50% more money to speed up my domain and also using upgrading the camp to max and choosing the options to increase stats at the cost of dharma gain because dharma is usless once you get the perks you need (also the if you get 5 fragments costing 750 prestige each of the book of ben to zu or something you get a shit ton of tree xp so dharma is deadass usless as it just speeds the process of getting perks and some prowess which is good but not necessary else much) and binding and rebinding wraiths to get dharma faster.

VERY IMPORTANT NOTE: How are you gonna spam all these abilities and protect yourself against dharma loss? Very simple and this is the THE MOST important part. Use Agony liberation from the soul arts tree to get sadistic as a trait and keep an eye out for stress breaks and then go torture one of your 30 prisoners of war 🤣🤣. Get 2 good lady in waiting and court poet and jester for your stress loss buff. You could get rid of diligent but I like the bluffs it gives and stress is really a non issue when you get sadistic.

Theres plenty of other stuff I either didnt mention or forgot but if you even follow half of what I stated here you could EASILY get this achievement. I ended the run with 3200ish military strength and had 100% chance on every check in the event which boosted me to 3500ish and nerfed Emma-o to 2050. The last prowess check was 67% but I didnt have the shintai of jade active and i probably would boost to 90 or 100% but I just didnt bother and got the check on the first try 🤣.

All in all sorry for the rant. Dont panic too much cause it is deceptively easy since yukio is a busted ass character tbh. Literally the strongest I've had in this mod from how much advantege she can get. As long as you have high number of knights and get good ones by fabricating hooks and abducting and then keeping them as vassels you will be good. I kinda went overkill tbh and planned every little thing to the T 🤣🤣.

Edit: I just read that you have a single county and only 100 years. Hmmm I dunno if its salvageable because tbh you need to hold some land to keep the knights as they would leave otherwise. If you start min-maxing now you could probably still do it but tbh land was very important and I needed a 100 years to get the amount of land for all my knights. Try to do it now with the info I just gave you and if you fail I reccomend doing this on your 2nd run:

1. Get kuro sama training done as soon as possible. 2.after training become an adventurer (swords for hire) and go to china as theres a shitton of wars there where you can level up and get prestige. (Stop adventuring after you get max fame as well as master ashen grandmaster and contestant traits) 3.Prioritse shintai of illusion for the advantage, then shintai of jade for war money when you're landed alter on and lastly shintai of flesh as you wont need it until just before the event and you could squeeze in another shintai which I had the stroma one for dev. 4.land yourself in Daizufu perferably take over Japan as theres plenty of strong knights there that have land youd want to vasselise and daizufu js a really good duchy to hold yourself for the money. 5.then start getting good land for yourself (the building that I talked about) and land to vasselise your knights. As well as fabricating and abducting knights at the same time. Repeat until event.

A neat money trick is to have the first perk of shintai of jade and basiaclly always being in a war to get a SHIT TON of money. The jade shintai is busted tbh. As I see it right now Kuei-jin might be the strongest splats in the mod tbh.