This was drawn from the complete dump of the Japanese Wikipedia on April 20, 2013 which was run through a morphological analyzer called JUMAN. This is a list of lemmas, not inflected forms, where homographs are counted as a single lemma. The lemma may not be the most common form.

There are two words appearing twice on the list: 有 (No. 1550 and 1939); 昼 (No. 1588 and 3999)

The 10,000 most frequent words accounted for 92% of all occurrences, the top 5000 accounted for 86%, the top 2000 accounted for 76%, and the top 1000 accounted for 68%.

In total, nearly 226 million words consisting of just over 163,000 lemmas were counted.

See also the list of lemmas ranked 10,001–20,000.