[1] It was discovered at the Jyoudo temple in Inno-shima (now part of Onomichi), Hiroshima Prefecture, Japan by Ekei Shounin in the Edo period.

[4] The allele sharing test performed by Tokurou Shimizu et al. (2016) gives its progenitors: pomelo (C. maxima) and the Kunenbo mandarin (Citrus nobilis).

[6] Hassaku fruit is medium to large (9-10 cm in diameter) and slightly oblate; seedy and monoembryonic.

[2] Several populations of the trees were infested with Citrus tristeza virus which caused stunted growth and destroyed the harvest after 15-20 years.

[2] Hassa-kun is a local mascot character which represents Inno-shima in Hiroshima prefecture to enhance image and promote tourism.