It sounds like " something alayk " (on you / upon you) or slamto alayk But as it's said this guy is Japanese, his arabic may be pretty good but is not PERFECT, so there's a big chance he mispronounces the words, coz the only answer to "Salam aleykom" is "aleykom salam" (long or short version) I don't know (and never heard) any other way to respond to that. Hope this helps

ok he said exactly " alikom el salam wa rahmat allahy " - so just what you have to now that " alsalamo alikom " it isn't the full greeting in Islam or arabic the full greeting is " alsalmo alikom wa rahmat allah wa barakatoh " = (peace , mercy and blessing of Allah/God be upon of you ) And you reply : " wa alaikom el salam wa rahmat allah wa barakatoh " = (peace , mercy and blessing of Allah/God be upon of you Too ) . * you can say the full one or the half one . ** the difference between allah and allahy it is a grammatical thing " el tashkil which but it by using ( el nahw ) " any way it doesn't a problem any way you will pronounce it , it will be got . # meaning of " el tashkil " it is signs you put it above or undre the letters to show you how it pronounces like َ / ً / ُ / ِ / ٍ / ٌ . Really I wish i could help you .

He said al salam w rahmat allah