So this one is really weird. It is in the class of Japanese tales where a human marries a human-like being or a being with a human form.
The Story
Long, long ago, on a sandy beach, lived a fisherman. One day, the fisherman went out on his little boat and began to fish. When he pulled in his catch, he found that he had caught a huge clam. Looking at the clam the man thought to himself, "It must have been a lot of work for this clam to grow so big. I think that I will let it go free." And with that, he tossed it back into the ocean. Later that evening, a beautiful woman appeared in front of the fisherman and said she wished to become his wife. The two of them soon married. The fisherman was quite happy, and his beautiful wife made the most beautiful dashi stock, and her miso soup was superb. However, she made him vow never to look into the kitchen while she was cooking. Over time, his resolve to keep his vow began to fade and his curiosity grew. He had to know how that delicious stock was made. Finally, he couldn't bear not knowing. He snuck over to the kitchen door and looked through the keyhole. To his surprise, he saw his dear wife standing over a pot and urinating into it. The fisherman was furious and confronted his wife. He was so angry that he chased her out of the house. His wife rushed to the sea, and when she got to the shoreline, she began to weep. Slowly she began to shrink and wither away until all that was left was a giant clam--the same giant clam that the man had saved. And then the clam returned to the sea.Citation