Note: items are listed in order of gameplay.

It is located at the Underground Temple entrance, near the stairs where you fight 2 or 3 Three-eyes monsters. See: Part 1: Reunion and Separation

South Area Map can be found in a treasure box in front of the gate of the Keep. Just after you unlock the blue crystal door, you will encounter a few spikey monsters, the box is in that area behind a wooden barricade. See: Part 2: The Keep

the Keep map, of course, is inside the Keep in a sentry room (where a Magic Mirror and a cocoon man located). When you enter the Keep's hall, there are three doors, two side and one main doors. The sentry room is in the second side door, see the map below:

See: Part 2: The Keep

Remember the Keep's hall with 2 side doors? Yes, the first one leads to the Keep's underground. Follow the storyline until you reach a hallway connecting to the Purifier Bell room. Between the hallway is another room with double doors, it is a meat storage room, walk to the left part of the room you will find a treasure box with map inside. See: Part 5: Keep Underground

Playing as Kaede, along the way to find Silver Plate, you will come across an archery range. There is a room behind it that can be accessed by climbing up a ladder and enter the door on the second floor (where the two Zombie Archers are standing). Inside the room has a Magic Mirror and a Magic Pool with a treasure box nearby, open it to obtain the map. See: Part 6: Found the Princess 

This one is in a room near the east tower. After you picking up Journal #6 (you cannot miss this file as you must pick it up because it blocks the door) and open the door, it leads you to a corridor. Keep running and ignore the first door (east tower) and the Samurai until you see the second door. The map is in the room behind a paper hanging on the wall. Simply press attack to cut through the paper and the map will be revealed. See: Part 8: From West to East

Demon World map is in a save room along with Bishamon Sword. Just after you defeated Marcellus for the second time, proceed to the next room. In there, you will see a Magic Mirror and a paper on the ground, it is the map. See: Part 10: Enter Demon World