Here are the ending condition for each episodes:

To trigger good ending in episode 1, talk to the kid in the orphanage and search for the event point (glows in red) on the second stage of the dungeon.
For episode 2, search the event point on the fourth stage of the dungeon after getting good ending on episode 1.
For episode 3, search the event point on fourth stage of the dungeon after getting good ending on episode 2.
For episode 4, search the event point on the first fight after getting good ending on episode 3 ( inside the church vs 4 demons ). Do not fight vs enemies before triggering the event point.
You will get a normal ending if you ignored the event point. If done so, the event points will not appear again at later episodes.


Here are the condition for each ending at the final episode:

Bad end - At episode 4, do not trigger the event point and get your party wiped out at the second battle ( inside the church vs Father Salade ).
Normal end 1 - Get normal end at episode 1,2 and 3. Clear the game.
Normal end 2 - Get good end at episode 1, 2 and 3. Ignore the event point at episode 4 and clear the game.
Good end - Check the event point on episode 4 and clear the game.