1. A computer-readable storage medium having computer-executable instructions stored thereon for creating a language model and performing Kana-Kanji conversion, wherein the computer-executable instructions cause a computer that executes the instructions to: receive a Kana character string; divide the Kana character string into substrings and generate Kanji candidates for each substring; obtain a plurality of trigram probabilities of Kanji candidates; determine whether any of the plurality of trigram probabilities is above a first threshold and select a Kanji candidate if a trigram probability is above the first threshold; when it is determined none of the plurality of trigram probabilities is above the first threshold: obtain a plurality of bigram probabilities of Kanji candidates; and determine whether any of the plurality of bigram probabilities is above a second threshold and select a Kanji candidate if a bigram probability is above the second threshold; when it is determined none of the plurality of bigram probabilities is above the second threshold: select a Kanji candidate based on cluster bigram probabilities of the Kanji candidates, wherein at least one cluster in the cluster bigram probabilities includes combining the same Kanji-Kana pairs with different parts-of-speech; and display the selected Kanji candidates based on an order of precedence.