There are 50 total collectibles to obtain. This goes towards Back to the past achievement:
None of these are missable you can chapter select after you beat the main story and get them on a different difficulty.
Note: You can get to a checkpoint and it should save and you can quit out.
The collectibles in this game are hidden some require to do certain puzzles. They will look like a medal most the time you will have to use a bow and arrow or slashing it to obtain it. It will break and float to you. They look like this:Stage 1 - Aku's Mine:
1. (0:09) Right before you hit the cave and after killing some beatle drones turn left it's by some pink crystals.
2. (0:31) After you kill the robo alligator with a gun. A house will explode. Jump to the next area and head far right. You will see a giant crate hit it and the collectible.Stage 2 - Boon's Castle:
3. (0:51) After the first gate opens from defeating all the enemies that appear. Head in and it's right in front of you by the Scotsman.
4. (0:59) *Bow required* Head left from the last one. You will see a hidden area with the Scotsman daughters and chest. Look high up with your bow all the way on the mountain is one.
5. (1:32) *Bow required* After you defeat some guys by an Aku door head up around but don't drop down on your right in a window will be one. Shoot it down.
6. (1:53) *Bow required* There will be a room with two chest head up the platform and through slicing knifes into a room with a broken table on the right. Head out from this room close to the edge outside look up with bow and shoot it from the green window.
7. (2:30) *Bow required* When you climb the grey mountain. You'll see on the left side Rothchild and his crashed ship behind this will be one to shoot almost into the pit.
8. (2:50) *Bow required* You'll see a red room with a chest and some chairs in it. Now head out and head past some shooting enemies. Once you see a tree and somewhere to climb up don't instead head towards the screen. Head downwards into the blue pool. You will see a cave in the corner. Head in and the collectible is in the back on the left shoot it.
9. (3:54) You'll notice a shop and a big tree. Head off the cliff by the shop it's in the back.
Stage 3 - Cave of the Ancients: 5/5
10. (4:06) *Bow required and jump upgrade* There are two chest before you climb a wall. Stand by the chest on the right you need upgrade high jump for this. Turn around and shoot the collectible in the distance on a hill.
11. (4:32) You'll notice a huge wall to climb head on the left and all the wall up. Punch it.
12. (4:44) *Bow and Explosive arrows required* In a room with spikes shooting at you. On the left door break down the wall with explosive bow and arrows. This is also where to find the great Samurai sword. You can break some of the spikes from above down to get across and jump over the gate. Hit it. On a ledge on left side.
13. (5:28) This is timed so be fast don't break anything. You will get to a spike wall dropping on you. Head to the end fast and right before the end turn around you will see it on a small ledge.
14. (5:55) *Bow and Explosive arrows required* Once you've slide down. Land on a rock turn around shoot the wall.
15. (6:20) *Bow and Arrows required* progress further you'll see exploding bugs come at you. Then a room of fire soon as you enter turn left and shoot the collectible by the spitting fires.
Stage 4 - Undead Cemetery: 7/7
16. (6:36) After your first fight of monsters punch all the doors from the tiny buildings. Behind one.
17. (6:55). When you get to the third area you'll notice a big coffin in the middle of the area. Break it.
18. (7:10) After fighting a wave of enemies you will notice a bridge and a big house drop down behind the bridge.
19. (7:30) *Bow and Arrow required* I missed this one, fighting some more enemies. Before you talk to the daughter you'll see a long fence area turn left and shoot it.
20. (7:44) Right before you get to a huge portal and after coming out of the cemetery on the left break all the coffins and rocks.
21. (7:55) After getting the last one you will see some stair going down head in this. Defeat enemies and break all statues there's one above too it's hard to hit it. Jump and hit it with fist or sword. Head into the last room by a coffin.
22. (9:16) Head through the portal head up giant stairs before entering the room head left. Punch it.
Stage 5 - Aku City: