[voltron]

^ If they did it next year, during their respective anniversary years, it could be a 20 & 25 celebration. At least for Ayu & Namie, not sure about KK.

I think Keiko for A Song is Born is Ayu's only female collaboration, if I remember correctly (and that was more a construct of all the charity singles, not so much Ayu pushing for it, I'm sure -- hence the solo version on I Am...). But generally it seems like most female singers don't collaborate unless they're very different stylistically (like Namie working with AI or someone similar).

I could see them doing something Colours-ish together (the uptempos at least), since that's more consistent with Namie's style. I can't really see them on a ballad together. MAYBE something slightly urban tinged, like Dream On, but I don't really see Namie going back that way.