I remember that there is a princess where you could interact with to increase their affection, and upon filling up 5 hearts, she will give you a gift (iirc a big sword).
The map of the game is like this, with o being a castle / base:
o o o o o
o o o o o
o o o o o
o o o o o
Etc. we start at the leftmost column, the rest of the castles were from demon king or monsters, and after starting the game, we will get attacked and have to defend the castles.