Re:in/guide

Diary
Enter the pink door. Go southeast until you see a red book resting among some trees. Interact with it to receive the Piece.

Wheelbarrow
Enter the pink door. Go southwest until you see a brown tunnel surrounded with sunflowers. Going in it will bring you to a teleport maze. After crossing the bridge, go inside the eastmost tunnel. Then, go inside the tunnel northeast to the one you came out of. Interact with the wheelbarrow to get the Piece.

Raincoat
Enter the indigo door. Find a frog that gives you the Raincoat Piece. (There is more than one.)

Ball
Enter the indigo door. Find a pink cloudy hole that takes you to some pink clouds. Go left and you'll be taken to some pink window doors. Go left again and you'll be in a red window room. Go in the middle of the three doors and interact with the huge bouncing ball to receive the Piece.

Unlocking Tamashitsuki
(The Raincoat piece is needed.)

Follow the Wheelbarrow Piece guide above to get to the Sunflower Tunnel Maze. Take the eastmost tunnel once you cross the bridge. Find an obscure tunnel surrounded by a cluster of sunflowers and a few rocks. Put on the Raincoat Piece and press Shift. All the rocks will come alive and one will move out of the way of the tunnel, allowing you to enter. Interact with the pole to get to the Downtown area. Make your way south through the forest, past the town, and into a forest again. Find a secret path (shown in the picture) and enter it. Move a cone by interacting with it. Avoid the chasers as best as you can through the path (you will have to jump over a hole by interacting with it at one point). Afterwards, make your way up the path and interact with the girl. After the event, go back to sleep and interact with the girl again in the nexus. Interact with the mirror to start playing as Tamashitsuki.

Duck Raincoat
If you go to the circle of five animals in the Animal Garden, put on the Raincoat effect and press Shift, the animals will turn into humans. Interacting with the Duck Girl will temporarily change the Raincoat's appearance.

Delinquent
In the Downtown area, in the city, there is a random chance of a person appearing in it, whipping a vending machine. Getting close to them will trigger a cutscene. Hanatsuki will hide from the person. They notice her and start creeping up to her until a jellyfish distracts them. After it, the person may appear again as a chaser. The jellyfish may also appear in various places around the city and can be seen with the Raincoat Piece.

Tamashitsuki's Pieces
(The Diary Piece is already in your inventory if you have the Diary Piece on Hanatsuki's part.)

Orthosis
Enter the gray door. Go southwest and interact with the doll to receive the Piece.

Artificial angel
Enter the gray door. Go roughly northwest and interact with the cage to go to the Cage Maze. From here, go Left, Right, Left, Right, and Left. Go to the left path and keep going until you see an elevator. Go up and you will be in the sky. Go left until you see a halo and wings. Interact with them to get the Piece. Keep going left to finish the event and end up back in the Nexus.

Fake Diary
Enter the brown door. Go southeast and find a red book among some murals to get a "Diary" Piece. This is not a real Piece, and in fact will make your playing experience a bit more "Glitchy" as seen in the next event listed.

Glitchy Menu Types
Getting the Fake Diary or the Artificial Angel Piece can sometimes make the menus change colors, change Tamashitsuki's FaceSet, change her name to garbled numbers and letters, or leave it blank altogether (these are only temporary).

Downtown Shenanigans
You can access the Downtown area as Tamashitsuki from the Cage Maze. From here you can jump over cones and gates. There isn't much beyond the cones and gates but the scenery will occasionally glitch out. You can also find Hanatsuki's house and jump up to her balcony.

Her Name
(It is strongly recommended to save before attempting this event.)

There is a 1/30 chance of Tamashitsuki "entering" the bed and glitching out the game when the dream bed is interacted with. Go north to find a glitched-out girl and then interact with her (Tamashitsuki is invisible so it might take some getting used to). Interact with two more glitched-out people to get teleported to an area where you can look up to an old movie screen. Interact with the screen four times to get teleported to a fake title screen. Wait a few seconds for a pair of hands to tear the screen apart. After some text, the game will purposely crash with the error "The file Her Name could not be opened".

( But if you copy and paste a file from the Picture folder, rename it Her Name, and then do the event again... )