I'm just going to write the guide here.
Your First Targets:
To start, I'd suggest focusing on two specific generals, one from each faction to corrupt. Go there, understand what their troops generally want, and provide them with the desired items. I'd recommend for the forest kingdom side Cypress or Persimmon. For the Yamano side, either Tsutsuji or Rindou. I recommend these four as their troops often ask for the most inexpensive gear at the start. Fortunately, getting an idea of what these general's troops want isn't very difficult and they often ask for items that fit the theme of their generals.
Cypress=Swords/shields
Persimmon=bows/crossbows
Tsutsuji=knives/guns
Rindou=talismans/caltrops
Your goal is to basically make a good impression on their men and sell enough wares or get fucked by them enough to have them endorse you as someone worth trading with. That's when you come face to face with a general and can start selling to them as well.
Corruption:
This is what you're all here for, of course, and here's how it works. Selling items and whoring yourself out spreads corruption. Now, it's not as easy to gauge corruption on a common soldier, but it's incredibly simple for the generals. Each general starts at 0 corruption and your wares will make that number go up. Once they reach certain corruption thresholds, the generals will begin to change. For women, they turn into half demons at 300, then full demons at 800. For men, they'll turn into women at 100 corruption, then half demons at 500, and finally, at 1000 corruption, they'll become full demons.
Early Game:
As I mentioned before, just focus on two generals. The reason for this is because of the faction war that is ever present throughout the game. The Forest Kingdom and Yamano are constantly fighting against each other and sometimes, one faction just has more momentum over the others depending on the generals in battle and weather. The reason you should corrupt two generals as soon as possible is so that you can manipulate who's fighting who more easily and help buy yourself more time. You see, a general that's ready to become a full demon or is a full demon already is willing to fuck you. However, having sex with a general will end the day early, in exchange, you'll receive a decent amount of money and no progress will be made in the war effort. That means more time for you to sell wares and you can stop a general who's too strong from curbing stomping the other faction and ending the game early. Keep in mind though, this only makes them stronger for the next fight which is why you'll want another general on the other faction to be corrupted as well.
Upgrades:
You can upgrade your character in various ways. I would recommend upgrading your negotiation skills and movement speed first. This game will require you to haggle and negotiate an acceptable price between you and the customer and the negotiation skill will make it easier to determine the highest price the customer is willing to pay. As for movement speed, this game is always in real time barring a few scenarios. That means you need to go to and from locations as fast as possible, lest you fail to do your business in time before the days end. The faster you can move the less time that will be wasted.
Crafting:
This is incredibly simple. Craft almost only weapons. Weapons are the most requested item by a country mile, in my opinion, it's not even worth your time training other employees in other skills with one exception, crafting crystals. Crystals are vital to creating the most valuable items in the game and you're going to need a lot of them, otherwise, selling wares will be next to impossible in the late game. The best ratio of crafters I've seen in my playthroughs are 3 employees dedicated solely speced for weapons while everyone else is speced for crystal crafting.
Employees:
This is also simple, hire people you want and upgrade the skills they're best at. Don't forget you own slaves as well and slaves that spend a long time in the slave pens will also have the opportunity to become corrupted into demon employees. Keep in mind, there are 3 unique and very highly skilled employees you can hire. They all have their own special introductory scene. Make sure you hire them as soon as their scene ends because they'll be instrumental in making quality items. Finally, don't forget to improve an employees salary later on. A better salary means they'll get more skill points to spend when they level up so make that decision early. Upgrading an employee who already has a high level is basically a waste of time as it will take forever for them to level up.
