CC BY 2.0 FR (some CC0)
Community sentences; includes Tanaka Corpus public domain data.
CC BY-SA 4.0 + GFDL (Wikinews CC BY 2.5)
Real-world encyclopedic and news-style prose.
Public domain works with attribution rules
Literary sentences and classic prose.
CC BY-SA 4.0 (EDRDG license terms)
Dictionary definitions, readings, parts of speech with share-alike.
WordNet-style open license
Synonyms and Japanese definitions for question generation.