[That gets Jiro to shake her head a bit with a very mild smile, even sort of laughing with a short huff through her nose, for some reason.
Probably because Momo's immediately assuming she's making Jiro worry more...]

No, don't worry! It's okay. Just the fact that you guys are here at all is really reassuring.
Not only that but having you with me right now is what's really putting me at ease, Yaomomo.

[It's really, really nice to have an actual, physical reassurance that the others are here at all.
Plus, y'know. She doesn't want Momo thinking she's doing a bad job at reassuring her or something.]

Anyway - you said you wanted to go to the bookstore, right?
How about we go together, and you can explain more of this place to me on the way?