Lamp
Fire you use to light up the street needs to go in a lamp. Campfires, matches? No, none of those work. You need bright, safe lamps to keep the street nice at night.
Picture these lamps lining the street, with their little fires burning brightly. Nowadays we don't have real fire in them, we use electricity!
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あかり, とも
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These street lamps were first used in とうきょう. It was the most advanced city after all. And more people were out at night in とうきょう than anywhere else in Japan. So they needed lamps to light things up!
Picture とうきょう, not lit up by all of the electricity, signs, shops, and things that light up its streets today, but by old-fashioned fire lamps!