Source: None, except for tons of 2ch threads
So some time ago there were threads on 2ch (Japanese messageboard) saying that Nacchi and Eri were recently in Thailand at the same time. Nobody had any idea what they would've been doing there (except maybe each other, j/k). I kind of forgot about it because there was no source, etc.
But damn, they're still speculating on 2ch why Nacchi was there.
Some suggestions: shooting a DVD. Shooting a drama. Shooting a PB. And so on.
The funniest part is, I still have no idea where they got the idea that Nacchi has been to Thailand in the first place. BUT HEY! Maybe we can also try to guess why Nacchi was in Thailand, if she was there.
I say Nacchi's cheating on me with tama. T___T (j/k)