Seiun Awards

The Seiun Award (Japanese: 星雲賞, Hepburn: Seiunshō) is a Japanese speculative fiction award given each year for the best science fiction works and achievements during the previous calendar year. Organized and overseen by the Science Fiction Fan Groups' Association of Nippon (日本SFファングループ連合会議, Nihon Esu Efu Fan Gurūpu Rengō Kaigi; abbr. SFFAN), the awards are given at the annual Japan Science Fiction Convention. It is the oldest SF award in Japan, being given since the 9th Japan Science Fiction Convention in 1970. "Seiun", the Japanese word for "nebula", was taken from the first professional science fiction magazine in Japan, which had a short run in 1954. The award is not related to the American Nebula Award.

From the Wikipedia article “Seiun Award”, licensed under CC BY-SA 4.0.

Check the official rules of the Seiun Awards for the current eligibility window, accepted formats, residency or language requirements and any entry fee. For most established prizes the publisher submits on the author's behalf, often with a limit on entries per imprint.

If you are self-published, look for an explicit statement that independently published books are accepted, and budget for entry fees and copies for judges.