Belt
There's a mountain coming out of the ground that you want to climb, but your forehead needs a towel for all your sweat. You don't have a towel, so you take off your belt and tie it around your forehead.
The belt is easy to tighten and it catches all the sweat before it can fall into your eyes. It isn't quite as absorbent as a towel though.
たい
おび
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The belt isn't absorbent enough, so you wrap it in your tie (たい) and then tie the whole thing around your forehead again.
It works! Your belt tied in a tie is the perfect invention!