Daion and Mugen were the same guitars. They were imported into the UK under different names and I guess the Daion Company you refer to was the US distributor. I think Mugen came first. I have a 1978 Mugen, I know a man who has a slotted head 12 string, I've seen a twin neck in Andy's in Denmark Street (London). There is a resident at Faversham club (I think) who has a grand concert size and (blasphemy!) he has taken the brass-coloured alloy nut off and replaced it with a bone one. One of the MacAlmans is reputed to have one but I've never seen it. One visitor to Dartford club approached me becasue he had one, and two people talked to me at Cambridge folk festival on year because they had them too. One of them should be traceable because he was from a bluegrass band from the South coast of Emgland and there can't be many of those. ALl are acoustic but mine now has an undersaddle piezo which sounds too twangy.

I haave been told that they will tolerate 13/56 strings but I trie d to use 13/58s on mone 'cos I liked the sound an destabilised the table and now can only risk 12/52s on it.

Mine says "made in Japan" on it and I have gleaned that they were the Japanese attempt to make a "supermartin" hence the very sharp sound.