Cylinder, Tube, Pipe
A bamboo stalk looks the same as a big ol' cylinder.
Compare the two things in your mind and make them the same.
とう
つつ
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Picture a cylinder shaped とうきょう. All the buildings are cylinders. The city itself is cylinder shaped too. Even... gasp! The people of とうきょう!
とうきょう is a really weird city now that they passed the cylinder law. Imagine it so deeply that it weirds you out.