The sort-of compound words ji-ari, ji-mori, and ji-nashi all begin with the term ji. The word ji, within the realm of shakuhachi, can refer to any substance that’s applied and adheres to the inside of the bamboo bore with the intention of tuning it (this often excludes lacquer or urushi because it’s not seen as being a form of tuning). Specifically, ji is used to augment the inner geography and affects play-ability (pitch, tone, and range). Looking at the second part of these words, ari means “to have”, mori is “a portion”, and nashi means “without”. [jiari 地塗り, jimori 地盛り, jinashi 地無し]
Historically, the first types of shakuhachi were jinashi, however, they were simply called shakuhachi because they were the only type at that time. Contrary to popular belief, ji was used in the bore of some shakuhachi during the Edo period (1603 and 1868) but it’s unclear as to whether or not it was used to intentionally augment the sound (jointing shakuhachi was also done during the Edo period). Around the end of the 1800’s, Araki Chikuo, AKA Kodo II (1823-1908) was credited as the first shakuhachi maker to systematically apply small amounts of ji to his shakuhachi (He did not apply ji to all of his shakuhachi, so it seems he used it only when he felt they would benefit). His students took this idea much further by applying ji to the entire inner surface of their shakuhachi, thus the jiari shakuhachi was born.
In short order, the jiari became the new standard, making jinashi largely relics of the past. This is reflected in the fact that jiari are often just called shakuhachi in Japan. However, jinashi and jimori are increasingly more popular, enjoying a full fledged renaissance in recent times.
Additionally, there are subcategories of jinashi such as hochiku (法竹 aka hotchiku or hocchiku) and Kyotaku. Hochiku were created by Ishibashi Gudo at the request of master Watazumi (1910-1992). They tend to be much longer and larger on the inside than previous shakuhachi in history, such as those used by the Komuso monks of the Edo period. Invented by Nishimura Koku, the Kyotaku are also longer bass or choukan shakuhachi which follow certain specific criteria, such as having all the holes in a straight line and of a smaller size. Lastly, these longer bass shakuhachi inspired various “spiritual successors” such as Ken LeCosse’s very large/wide Taimu or “big nothing” shakuhachi.