AJ-JpnRa Tool
「AJ-JpnRa Tool」 is Japanese text readability analysis program.
...You can analyze Japanese-Text Readability with the length and Chinese character level of the text by using the AJ-JpnRa Tool.
And Chinese character level is analyzed by the database(AJ-JpnRa Tool), which was built according to essential Chinese character education guideline of Japan elementary and middle school and JLPT; 学年別漢字配当表, 常用漢字.
Essential Chinese character education guideline of elementary school is called 学年別漢字配当表, has 1006 chinese characters. And middle school one has 1130 chainese characters. If you combine essential Chinese character of Elementary and Middle school, you can have the regular-use Chinese characters.
...