Kagi is a native Japanese word meaning 'key' or 'lock' (the two are usually not clearly distinguished). In Chinese characters it is written . This is how it is written in the signs below:
However, is not the simplest of characters to write, and there is a tendency to write hiragana or katakana:
A Google search in August 2003 revealed the following distribution:
The above figures are only a very rough guide as includes a very large number of occurrences in compound words (such as kenban keyboard) and thehiragana includes parts of words that contain the sequence kagi.