What kind of cuttle is this?

On a night dive last night this little guy at about 3 or 4 inches long was skirting a reef wall near the bottom at 50 feet. The white picture is from when he didnt notice us, the brown picture was when he began to turn and seemed alarmed. After that photo I left him alone and was concentrating on a particularly nasty sea snake that inhabits this area and will strike after chasing you for up to 20 feet or so. The little cuttle reappeared along the bottom heading right for me and was now brilliant colors of dark reds, yellows, browns etc. I have never seen this cuttle here in Japan unless its a juvenile form of the Broadhead. However, I have seen other junenile Broadheads and they are similar to their adult forms in my opinion which this particular cuttle is not.

There are two closely related species which are justifiably called flamboyant or paint-pot cuttlefish, Metasepia pfefferi and M. tullbergi. The first species is found from tropical Australia over to Papua New Guinea. The second - which is what you photographed - lives from Japan over to China & down to the Gulf of Thailand, and the Philippines. There's more information on them at ftp://ftp.fao.org/docrep/fao/009/a0150e/a0150e05.pdf