| "Shi" in hiragana looks like a fishhook.
Here it is, in both types of kana, in ASCII art:
Hiragana: Katakana:
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If you own a Japanese dictionary with the entries in a-i-u-e-o order, and have a Japanese pen-pal or read manga (meaning you USE the dictionary) you will soon notice that "shi" is the kana with the most entries of all under it. Probably has something to do with the fact that "shi" has to work for ten morae (shi, ji, she, je, sha, ja, shu, ju, sho, jo) whereas most kana work for only one or two morae. But then again, it is unusual for all those morae to actually get used! (Try looking up words that begin with the kana "mi" to see what I mean.)
The letter "shi" is never used on Japanese license plates, due to the fact that the Japanese word for death is "shi".
The letter "shi" is sometimes pronounced as "si", which is, in fact, how it is often romanized. | 
