There are many versions of the Japanese folk-story, 鶴の恩返し (tsuru no ongaeshi) the Crane’s Return of Favor, but my favorite is the one where a poor young villager finds a ツル (tsuru) crane caught in a hunter’s trap.
Feeling sorry for the beautiful creature, the villager set the ツル free:
Later, a lovely maiden who got lost in the woods visited the villager’s home and they fell in love. They got married and eventually climbed out of poverty by selling the finely embroidered robes the maiden secretly wove in her loom. With their first profit, the villager bought her a gleaming golden comb.
Her husband never understood why she made him promise to never watch her work, but he obeyed her wishes until he noticed her health deteriorating. With every dazzling new robe she produced, she became more haggard and wan. Concerned for her health, he broke his promise and opened the door while she was working.
Instead of a woman, he discovered the ツル he once saved weaving its feathers into a robe. Unbeknownst to him, the ツル wanted so desperately to return the villager’s kindness that she made a deal with a mountain hag to become human. However, now that he had seen her in her true form, the spell was broken and she could no longer transform.
Upset and dismayed, the ツル flew out of the house determined to never return. However, sensing that this was her intention, her husband quickly threw her golden comb into the air so that she could have something to remember him by.
Smiling, シ (shi) “she” circled around to catch his precious gift in her beak before flying off into the horizon.
The point of this post is not so much the moral of that story, but that the katakana tsu (ツ) has more vertical strokes like a ツル's vertically stretched wings while flying up and away from a hunter's trap. xD
Meanwhile, シ (shi)has more horizontal strokes like how a crane would circle horizontally to catch her comb and looks like a mixture of the expressions “she” would make:
:-| (why did you break your promise) and
:-) (thank you for everything ‘til now).