15a Basic unit of ammunition for Japanese army during the second world war(9) K???E???N
31 Embryonic form of an insect(5) I????
39d A native American language found in Colombia or Panama(7) ???O?N
43d Where the Spanish Royal family traditionally spend their summer holidays(5) ??L?A ( I can only find Majorca for this!!!)
Does anyone have any ideas what the words that are missing in this crossword are and their connection? I only have UP HELLY AA as one answer but am at a loss for the others!!