During the 16th and 17th century, Portuguese Jesuits had undertaken a great work of Catechism, that ended only with religious persecution in the early Edo period (Tokugawa Shogunate).
Many of the words which were introduced and entered the Japanese language from Portuguese and Dutch are written in kanji or hiragana, rather than katakana, which is the more common way to write loanwords in Japanese in modern times.
[15]) Some word pairs that appear similar are actually false cognates of unrelated origins.
It is often suggested that the Japanese word arigatō derives from the Portuguese obrigado, both of which mean "Thank you", but evidence indicates arigatō has a purely Japanese origin,[22] so these two words are false cognates.
[23] In turn, arigataku is the adverbial form of an adjective arigatai, from older arigatashi,[24] itself a compound of ari + katashi.