I think Saori brought these guys back from the Near Shore during some kind of... pet adoption day? [A cat cafe was having an event, actually, but he wasn't present for it.] There are a lot of strays out there, too.

[And, you know, come to think of it,] With how many temples with cats there are around, there are probably a good number of strays out here, too.

[What are the chances that other pet cats have found themselves in a similar situation to the ones he's chasing down? Where their home just up and disappears, leaving them behind? It probably happens all the time.]