Wash
A tsunami previously gave everything in this town a good wash. There are many laundromats in this town, so when the previous tsunami hit, all of the detergent mixed with the water and gave everything a good wash.
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It wasn't just the town that got a wash, it was the centaurs (せん) too. (Centaurs happen to live in this town.) And being half horse, centaurs have a lot of hair that needs washing. Luckily, the soap tsunami gave them a good wash too.