1809: arigato and obrigado Nov 27, 2019

A number of Japanese words are of Portuguese origin, including 'tempura'. The idea, though, that 'arigato' (ありがとう) comes from 'obrigado' is a myth, although they both mean 'thank you'. The history of Portuguese exploration before Japanese isolationism also led some to think this was when the word was adopted, but actually it can be attested for in Old Japanese. At that time 'arigatashi' had the meaning of 'difficult to exist', which led to the meaning of 'rare; special', and then eventually 'nice to have; welcome'.
For more on surprisingly similar words, read about 'dag' and 'dog', derived a world apart, or read about Spanish influence on Tagalog here.