Japanese thought is non-dualistic, which means they believe entities do not exist in opposition to one another or separate from one another. 

When Japanese scholars encountered the Western ideas of “citizen” and “individual self” they grappled with how to describe a person as separate from society. What is a person if not for the relationships they have with one another and the wider world? “Kojin” is the term thy settled on for “individual,” and comes from a need to emphasize the dualist nature that Western texts intended:

Nakamura Masanao’s translation of On Liberty in 1871 provided a more concrete phrase with a Japanese pronunciation. He translated “individuality” as ikko no jinmin (⼀個ノ⼈⺠). Jinmin, as we saw in the first translational moment, was used as a substitute for the word “citizen” in Fukuzawa’s early texts and also in Nakamura’s translation of Self-Help. It emphasized the particularity of the single person in differentiation from the whole. Ikko doubles down on this particularizing, insisting on the separateness of the single person. Interestingly, the kanji ko 個 is a combination of the elements for “person” (hito ⼈) and “hard, ” “indivisible,” or “fundamental” (katai 固い). Japanese requires special words for the counting of certain objects. Ko (個) is used for counting individual objects of relatively small size that do not dissolve into one another.

Full etymological history described from source above, and in more depth here.

There are many ways of engaging with the world, and what I take for granted as individualism – my sovereign self – is just one way of looking at things. What is a person if not for the relationships they have with one another and the wider world?