I use Rikaichan obsessively and have noticed that it uses non-standard level designations for kanji. For example, it has kanji levels numbered 8, 9, and even 10!
I thought that kanji grade levels basically meant the corresponding grade in Japanese schools where those kanji are learned. My DS kanji program (Kageyama Method) divides the 1945 jouyou kanji as follows:
1年生 80
2年生 160
3年生 200
4年生 200
5年生 185
6年生 181
中学生 316
中学上級 286
高校生 337
Could somebody provide the number of kanji that Rikaichan thinks are levels 7-10? I suspect that 7-8 are the rest of jouyou, 9 is jinmei and possibly other everyday kanji that are not in jouyou, and 10 is something even more rare.