Japanese IO uses the JMdict, JMnedict and Kanjidic2 dictionary files, which are the property of the Electronic Dictionary Research and Development Group and used in conformance with their licence.
Example sentences are from the Japanese Tatoeba corpus, licensed under Creative Commons CC-BY.
JLPT level information is from Jonathan Waller's Japanese Language Proficiency Test Resources page.
Texts in the classics section in the public domain from Aozora Bunko. Author and text metadata (作家別作品一覧拡充版) is unmodified from Aozora Bunko and used under a Creative Commons (CC BY 2.1 JP) license. Author and text descriptions/excerpts are from Wikipedia and used under a Creative Commons (CC BY-SA 3.0) license. Author images are from Wikipedia and in the public domain or used according to the license indicated.
The "Give My Regards to Black Jack" manga is made by Shuho Sato and is copyrighted by Sato Manga Works Ltd.
Japanese IO is copyright © 2021 by Atilika Inc. All rights reserved.