Characters first seen in Kyushu and neighbouring Japanese islands (5)
I believe the answer is:
kanji
'characters' is the definition.
'first seen in kyushu and neighbouring japanese islands' is the wordplay.
'first seen in' indicates taking the first letters.
The initial letters of 'kyushu and neighbouring japanese islands' is 'KANJI'.
(Other definitions for kanji that I've seen before include "Oriental character" , "Japanese writing system" , "Chinese character in Japanese" .)