It's true of freshwater clams. You can't make good miso soup with freshwater clams if you don't clean sand out of them.

Yaro Abe

From cartoon "Midnight Restaurant, 13". A man met a woman he adored as a junior high school student again for the first time in 40 years, and got married to her. His wife got married for the third time and is away for a while to care for her daughter's delivery. The husband has delusion that his wife is meeting an ex-boyfriend, and hurts her feelings on the phone. When he confesses his regret to the owner of the restaurant, the husband is told to go to pick her up because she must feel hard to come home missing "a good chance to return." It is important to wash away the thing hooked on her mind first.

"May 31  2019

from “Oriori no Kotoba” by Kiyokazu Washida, The Asahi Shimbun"