He's almost reminding Ritsuka of a Berserker, really. Just in the whole... Getting fixated on something seemingly at random and then being utterly unstoppable once he does thing. The trick with those types is to get them pointing in the right direction before they go off, so...

"Right, so let's go! Over here!"

And she's going to just steal a page right out of Vash's playbook and grab him by the wrist (or sleeve, or whatever's most convenient, really) to tug him toward the nearest promising-looking booth she's been able to spot. Will she actually be able to force him to come along? Not a chance. Will doing so at least keep his attention on her and where she's going long enough to avoid getting sidetracked by the many (many) distractions?

Well, it's worth a shot!