Genjiro Koi is an old and very well respected koi farm located in Kawaguchi,  and is now operated by Takashi Kobayashi – a fourth generation breeder. The farm was originally founded by his great grandfather who is famous for being one of the first breeders of Kohaku and originated the Tomoin and Sensuke bloodlines. Genjiro is also famous for their production of Sanke as well.  They are likely the only farm to still uses a pure Sadazo Sanke bloodline as broodstock.  

They are also well known for producing quality metallic varieties as well such as Kujaku, Kikusui and Beni Kikokuryu.