Densha (Train) is a freeware adventure game by Field of the Wheat made in WOLF RPG Editor.
Forwardbound it goes!
Nothing else to be done.
No other way about it.
Important: Please refer to the included files for certain Japanese-centric elements, particularly the final puzzle.
(Content Severity: Very Mild)
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 Japanese page
First, a direct walkthrough taking you through the whole game.
Car 6: Go left to Car 12.|
Car 12: Walk to the left, and the man will turn the plate to warp you to Car 21.
Car 21: Walk into the top half and go left to talk to the man from across the barrier for a dining ticket. Walk to the left on the bottom half to have him warp you back to 12.
Car 12: Walk into the top and, go left, and talk to the man to give him the ticket. Pick up the stepladder and carry it to Car 6.
Car 6: Place and climb the stepladder to get the pearl on the dresser. Place it in front of the plate on the wall and turn it twice to reach Car 9.
Car 9: Get the mosquito coil. Go right to Car 4.
Car 4: Place the mosquito coil and leave. Re-enter and get the [Ki] plate which drops out. Go right twice to Car 0.
Car 0: Open the curtains to the right. Flip the "TV" switch by the man off. Return to the stepladder and turn the plate to go to the Inbetween (gray actual-train area with numbers out the window).
Inbetween: Talk to the mononoke man for a watermelon. Flip the plate to go to White Space.
White Space: Talk to the mononoke man to begin watermelon splitting. The man directs you away with "?" directions, and the woman directs you the right way with "!" directions. You get the silver cross key from the split watermelon. Flip the plate and turn it to return. Walk all the way left to Car 21.
Car 21: Talk to the chef for a pot and ladle. Walk all the way right to Car 6. (Turn the plate twice if it's Car 9.)
Car 6: Scoop the butter into the pot. Walk back to Car 21.
Car 21: Give the chef the butter. Walk right to Car 3.
Car 3: Use the nata to cut the grass on the left as well as the red flowers. Go to Car 6.
Car 6: Remove the plate. Place the [Ki] plate and turn it until you go to a room of trees.
Tree: Use the nata to cut the yellow flowers. Remove the [Ki] plate and put the other plate back. Carry the stepladder to Car 21.
Car 21: Climb the stepladder and flip the plate to make it 51. Turn it twice to go to Car 15.
Car 15: Use the ladle to scoop out the screw. Turn the plate twice to go to Car 51.
Car 51: Carry the stepladder over to the clock and use the screw. Go left twice to Car 62.
Car 62: Place the yellow flowers in the vase. Check the cupboard underneath for a plate half. Carry the stepladder to Car 62 and turn it to 26.
Car 26: Place the red flowers in the vase. Check the cupboard underneath for a plate half, making the  Plate. Turn back to 62 and carry the stepladder right to Car 52. Turn it to 25.
Car 52: Check the necklace and add the missing pearl to take it. Turn to 25.
Car 25: Place the necklace on the table for the gold cross key. Remove the plate and place the  plate.
Car 37: Step into the middle for a scene. (You can now pass through Car 37 freely.) Go to Car 10.
Car 10: Open the door with the cross keys. Get the  plate. Carry the stepladder to Car 3.
Car 3: Remove the  plate. Place whatever extra plate so that you have [Ki], , and . Walk all the way left to Car 71.
Car 71: Place the plates to spell "sa-yo-na-ra." Consult "sayonara.png" in the folder for how it should look. When a plate is correct, it "projects' to the sign in the background instead of being blank.
Exact solution from left to right: 1. Place [Ki]. 2. Place . 3. Place . 4. Flip then turn the fixed  plate.
Second, a guide for how to get each particular item, as the order is pretty flexible.
Items in italics are used along the way, while items in bold most be collected for use in the final puzzle.
Nata: Bring the watermelon to the mononoke man in White Space. (Successfully split the watermelon to keep it.)|
Pearl: Use the stepladder to get it from atop the dresser in Car 6.
Butter: Get the pearl to make piles of butter in Car 6. Talk to the cook in Car 21 for the pot and ladle, then use them to collect the butter.
Mosquito Coil: Turn the plate in Car 6 to make it Car 9, then it's just lying there.
Dining Ticket: Walk into the top half of Car 21 and go left to talk to the man from across the barrier.
Pot & Ladle: Get the pearl to make piles of butter in Car 6. Talk to the cook in Car 21.
Screw: Flip and turn the plate in Car 51 to reach Car 15. Scoop it from under the machinery with the ladle.
Plate Half (1): Put the red flowers in the Car 26 vase and check the lower cupboard.
Plate Half (2): Put the yellow flowers in the Car 62 vase and check the lower cupboard.
Necklace: Use the pearl on the necklace in Car 52.
Red Flowers: Cut them with the nata in Car 3.
Yellow Flowers: Place the [Ki] plate somewhere to reach the tree room and cut them with the nata.
Watermelon: Talk to the mononoke man in the Inbetween after using the mosquito coil.
Silver Cross Key: Bring the watermelon to the mononoke man in White Space and split it open.
Gold Cross Key: Place the necklace on the table in Car 25.
[Ki] Plate: Get the mosquito coil and use it to remove the mosquitoes in Car 4. It falls out of the tree afterward.
 Plate: Get the nata and use it to cut the grass in Car 3. Use the stepladder to reach and remove the plate. (You'll need to use the complete  plate to bring it out of the Inbetween.)
 Plate: Get the gold and silver cross keys and enter the door in Car 10.
Always moving forward, not backward.