"k*ik*n" or, In Japan, single-letter errors are fatal

I've been observing for awhile that Japanese is far more sensitive to single-letter mistakes than English. In English, while there are some words that are only a single letter apart (e.g., ball, bell, bill, bull), usually there's quite a distance between words. If you try to change the third letter in 'ball,' 24 out of the 25 possible changes are gibberish; only "bail" is a real word.

In Japanese it's quite the opposite, and because of some recent vocabulary I learned I came across a great example: k[ae]ik[ae]n. That is, take two-syllable words in Japanese where both syllables begin with k, one syllable ends with i and the other with n, and the vowel in the middle can be a or e. There are four such possible words, and it turns out all four are real words:

会見	かいけん	kaiken	interview, audience (as in "audience with")
経験	けいけん	keiken	experience
快感	かいかん	kaikan	pleasant feeling *
警官	けいかん	keikan	policeman

* In fact, かいかん has another full homonym, 会館, meaning "meeting hall"

And it keeps going. If you reverse the syllables and go for k*nk*i, there are four other possible words, all of which are also real words in the language:

関係	かんけい	kankei	relationship
県警	けんけい	kenkei	prefectural police
官界	かんかい	kankai	bureaucracy
見解	けんかい	kenkai	opinion, point of view

This definitely starts to show why the Japanese are so fond of wordplay and puns; the language is just full of opportunities to use single-letter errors for humor! But man it's tricky when you're learning.