Many variants were found in the "Nihonbare" 's stock farm of Shimane Agricultural Experiment Station in 1973. Most of them were characteristically longer in culm length and later in heading time compared to "Nihonbare" pure plants.
Progeny teste of eight variants were conducted from 1974 to 1977. The segregations of culm length, heading time and/or awn density were identified in five of eight variants. It is suggested that this contamination was caused by the outcrossing with other stock varieties, perhaps in 1972.