Question about ayu's song titles
 

I've noticed in a lot of her song titles and album titles she uses some sort of hyphen or dash to separate subtitles/extra information, for example 'Marionette -prelude-' and 'A Best 2 -White-'

Just wondering if anyone can tell me exactly what these symbols are? I've tried researching it and it doesn't come up on any Japanese grammar sites. I know all about using wave dashes for subtitles but these I haven't heard of. Are they hyphens? en-dashes? I've tried copying and pasting them from her website but they only use a hyphen-minus, which is really just a keyboard shortcut and not a real symbol.

Anyone know?

Thanks :)