Just an hour or so earlier...
Tamamo usually doesn't bother her over things, let alone so incessantly. But she's been trying not to laugh as she pointed Sinnah to this out of the way spot near Weiss's haunt for a week. So.
Either her favorite crytid-hunt companion has gotten herself into some embarrassing trouble, or something very interesting is happening here.
...Ah, a rift, closed for nearly a week. That'd do it.
Sinnah is, perhaps, one of the only people who could reopen one of these. At least, so long as any real trace remains. It's a few days of delicate work building up the natural mana flows in the local are to the same crescendo that opened it in the first place. A dozen large-scale spell circles in half a dozen locations, which she flits between with the latest version of her fly spell.
(She's not worried about going home. Weiss is here somewhere, and she has the Long Road Home, one of Tamamo's special rituals. And if it comes to it Sinnah knows how to get to the same place, if more... Laboriously.)
She's going to be relatively low on energy by the time she finishes but that's fine. It's only really interesting as an academic exercise in proving she can do it, at first. How annoying it would be, if Tamamo is merely pranking her.
But then the portal opens and she drops down into the city after Weiss, wearing her full exploring kit, including a number of shields, wards, contingency-spells, wands, and a whole lot of scrolls.
...Oh-ho-ho. She's never gotten the chance to go to an Otherworld, merely to interview Otherworlders. She feels her annoyance evaporate away to interest and even excitement, not that it shows overmuch on her face. This was well worth the trip.
She activates a weak divination looking for the largest concentration of magic in the strange city, and flies towards it.