After registration: how long the right lasted

The detail pages of the variety registration database carry more than origin and characteristics. They also carry the term of the breeder's right and the date on which that right was extinguished.

Some extinguishment dates are marked "term expired"; others are not. Where the mark is absent, the right ended partway through its term. The documents give no reason, so this site gives none. We set out the dates and nothing more.

Few rights ran to the end

This site has consulted the registration documents of 53 varieties. They break down like this.

The extinguishment field	Count
Marked "term expired"	13
A date, but no mark (ended partway)	38
Empty (still running)	2

Most of these registered varieties were let go before the right was used up.

The shortest is one year

Shortest first, from registration to extinguishment.

Variety	Registrant	Term	Registration to extinguishment
Inochinoichi	Takashi Imai	25 years	1 year
Hamakowase	Nagano Prefecture	15 years	2 years
Kounomai	Hyogo Prefecture	15 years	3 years
Futagoboshi	Kenji Inomata	25 years	3 years
Kamiakari	Akihiro Matsushita	25 years	3 years
Seikiwan	Masaki Oikawa	20 years	3 years
Ayanohikari	Saitama Prefecture	15 years	3 years
Murase No.1	Yoshitaka Murase	25 years	3 years

Inochinoichi's right ended one year and one day after registration. A 25-year right, finished in a year.

Registrants are not only prefectures

Registrant	Count
Prefecture	29
Company or corporation	10
Individual	14

The corporate names are Mitsubishi Chemical, Japan Tobacco, Hakubaku, Nakajima Mio Shoten, Furusato Kawachi, and the Aomori Prefectural Industrial Technology Research Center. Rice varieties are not registered by experiment stations alone.

One person registered four varieties on the same day

Four of the fourteen individual registrations carry the same name, Tadatoshi Isayama.

Variety	Filed	Registered	Extinguished
Isayama No.1	1996/03/04	1999/11/25	2005/11/26
Toyohikari	1996/03/04	1999/11/25	2005/11/26
Yayamamochi	1996/03/04	1999/11/25	2005/11/26
Oganemochi	1996/03/04	1999/11/25	2010/11/26

All four were filed on one day and registered on one day. Only the extinguishment differs: Oganemochi's is five years later.

The origin sentences overlap too. Isayama No.1 and Toyohikari do not differ by a single character, and neither do Yayamamochi and Oganemochi. The four fall into two pairs, and within each pair the registration document's origin is the same sentence.

Terms of 15, 20, 25 and 35 years

Term	Count
15 years	21
20 years	23
25 years	7
35 years	2

Only Nasuhikari and Issunboshi carry 35 years. Both were registered in 2007, and both have an empty extinguishment field. Torinoizumi, registered in 2008, is given 25 years. Why these two alone are 35 is not written in the documents.

Between one and twenty-two people bred them

The longest list is Ajikodama (Niigata) with twenty-two, then Koihime (Aomori) with sixteen and Yaekogane (Nagano) with fifteen. The shortest is one, and varieties registered by an individual almost always list one.

Among prefectural varieties the shortest is Fukkuramomoko (Okayama) with three. Even within "a prefecture's variety" the list runs from three names to twenty-two.

Three patterns in what the comparison names

A registration document closes with "distinguishable from … by …". The varieties named there fall into three patterns.

Pattern	Examples
Both parents appear	Haruru, Goropikari, Fukkuramomoko
One parent appears	Kounomai, Haresugata, Saga No.1
No parent appears	Natsushizuka, Omachikane, Torinoizumi

A parent is not always the yardstick.

The longest list of comparisons is Toyamanishiki's: Koshijiwase, Honenwase, Gohyakumangoku and Koshihikari. Gohyakumangoku is a sake rice. A sake variety turns up as the yardstick in the registration of a table rice.

About the sources

The dates, head counts and comparisons set out here were taken from each variety's own registration document. No new source has been created; the source list on each variety's page links to its registration.

The transcription is kept at data-src/rights-53.tsv. The table was taken by opening all 53 records on 8 October 2026. For the varieties whose rights are still running, an extinguishment date will appear later.