That's kinda what I was thinking, the Korean use of Neh can be flexible enough to be used as a past particle. The Japanese like to ignore or outright white wash the influence and impact of Korean culture on the island.
i dont know if it really came from portuguese, but 'né?' as a contraction for 'não é?' is a real thing, and it really does match the use of japanese 'ne' and english 'innit'
More like the Indians, more specifically the early Indo-European. You can trace the migration of Indo-European by language groups. Sanskrit was carried from India to Mesopotamia, into the central step, to the northern caucuses and even as far as the eastern step and into Manchuria.
It's possible that this particular particle was transferred from central step people like the scythian to eastern tribes of the xiongnu who eventually settled in Southern Korea, leading to the yayoi migration to Japan.
I think I'd like weebs a lot more if they randomly threw in some English chav speech and culture in the mixer now and then 😄
..oh fuck. I just made myself realize that chav weebs probably DO exist and I don't know if that's hilarious, horrifying or both! I'm leaning towards the latter 😬😆
This reminds me of a joke that the Rioplatense spanish version of tarot cards would probably have "El Boludo" for the fool , which is basically "The dumbass"
I wouldn't say it comes from Korean, more like it and its analog in Korean probably have a shared origin due to the mixing of ancient Koreanic and Japonic peoples pre-migration and during migration. It may have come from a different language that doesn't exist today, it may have originated in proto-Korean or proto-Japanese, or Koreanic and Japonic language speakers may have just changed each others language in a way which caused the particle to emerge in both languages (which is certainly plausible given how much they influenced each other's grammar in general).
From what I've researched online, the consensus among linguists is that it is not Portuguese in origin. I haven't found anyone opining this other than this tumblr user in fact. Anything is possible, but this seems completely ungrounded.