It’s All About the Botanicals, Dude.
The history of Gin in Japan starts with Suntory launching a London Dry style gin called Hermes Dry Gin in 1936. In 2016, The Kyoto Distillery launched the first craft gin made with Japanese botanicals called Ki No Bi (which means seasonable beauty). On its tail, Roku was launched, a gin also made from Japanese botanicals, launched in 2017.
While western Gins carry various tones of juniper, aniseed, lavender, orange, rosemary and other ingredients, Japanese Gin typically uses fewer ingredients and importantly, uses Japanese native botanicals.
Sakura (cherry blossom), Hinoki (Japanese cypress), Gyokuro (a variety of shade-grown green tea), as well as other roasted green teas are used but the list goes on.
Sakaki, an evergreen tree sacred to Shintoism gives Japanese Gin a very "green" aroma as well as Sansho (a type of Sichuan peppercorn with its lip-buzzing tingle) and many varieties of Japanese citrus, like Yuzu, Hyuganatsu (New Summer Orange) or Kumquat are used. Umami, a cooking seasoning made from seaweed and mushrooms is also used.
The base alcohol also varies from western gins. Shochu, made from potato, sweet potato or sugarcane is used.
Hyuganatsu is weird. Hyuganatsu (“Hyuga”is the ancient name for Miyasaki Prefecture and “natsu” means summer) originated in Miyasaki Prefecture in Kyushu. It seems that a Hyuganatsu sapling was found growing in a Miyazaki garden in the 1820’s. The theory is it’s either a mutated Yuzu or a natural hybrid between a Yuzu and Pomelo.