Couple years ago, for this reason, not the kai reason, but any phonetic-word-attempt which gave me tons of kanjis, for same phonetics, I said, Japanese Language has so many synonyms, (perhaps this is anti-synonym, but in my defense, I don’t remember exact word I used, its a memory retrieval, you see) and still Japanese Language unites them all and makes into one language; we can also do this for Indian language.
Indian (Language) would be far easier (than the complexity of Japanese) in that, given, lets say, jack-fruit will have 8 different words only, across India, then, we have to put them all into one syllable-alphabet unit (that can be newly defined, because now we have at-least 20 ways to define) eg Hindi: kathar/kathal, Odi: panas (Telugu also Panas, I know, I asked this to my friend 15 years ago, he was from AP, his name Venkateswaralu Goruganthi, funny fella with thilak on his head, see since when I am doing my language research?) I don’t know more language, lets say: Gujurati: xyz.
Then take all Indian Language and list these into one unit. That unit would be given a special phonetic tag. (Because we don’t have any) The reverse of this has been accomplished by Japanese. By having each meaning for a single phonetic or syllable unit as a kanji (or pictorial unit) they have unified language. Back then I said, 20 some synonyms, (so many = 20) Lets count today.
As if a coincidence I found 20. Although, there would be, some redundant issues here (eg 買い and 買 ) and a few more may be left. (eg I remember, now I know some Japanese Language by memory: kai = write, kai in kaishi = begin). Lets see what we found in Japanese for kai; each of the following is kai, with different meaning. Only one is (sa)kai and couple are not known (just kai, in 2nd line), from where I am searching. Lets then, give their meaning.
会 回 海 買い 貝 階 解 界 介 下位 峡 怪 甲斐 飼い 買 櫂 快 歌意 交い 科医
Meeting Time Sea Buy Shellfish Floor Solution Field Through Subordinate Isthmuses Mystery Worth Domestic Purchase Paddle Comfort Kai Kai Family-physician