Your objective is to clear the fisherman’s house location on the map and enter it. While by the river, you’ll notice a girl drowning. Tap on the Neko to save it.
The issue might be that the quest isn’t triggering properly. If the character has already found the cat but can’t proceed, it could be due to in-game blocks. Try checking if all the conditions for the next quest stage are met, or restart the game to reset any potential errors.