Arigatoyou can get upgrades by talking to workers in the castle when you have enough resources.
you get resources from investing in shops, inns, and farms.
to invest in shops, you need to find their sign post (usually inside, near the cashier. some of the farms can be a little harder to find.)
You can get Manpower, a none-decreasing resource, by talking to the black dame, and choosing the option. if the option doesn't come up, try to progress the plot a bit, and try again.
Just finished the game.can someone upload current full saves for the game