[Time to deal with Kiseki's menacing creatures again! Except this time, they might not be so menacing. The lake and river are a little more lively than usual, as the fish population in them has increased overnight. Some of them aren't even freshwater fish, so what are they doing there? Not waiting to attack anybody, no.
All along the park and the river banks, there are fishing rods and other tools set up, as well as anything you'd need to get a fire going, and grill your food... You get the point, I'm sure. Whether you want to have an outdoors lunch of freshly caught fish, or wish to stock up on them for later, or even want to try and keep one of them as a pet, it's clear today is meant to be spent by the water. Just in case, the Usyagi will notify anyone who's missing out on the fish gutting fun, so no worries there.
To the delight of certain questionable residents, there's a bonus brought by the presence of the fish... Most of Kiseki's roaming stray cats will be drawn to the river and lake, either to catch their own meal or to steal some from the people around. So if you're not much of a fishing person, or can't cook at all, you could still hang out with them.]