Koishi has a fishing rod.
So I click on this one and only button. Then I click on it during the casting/reeling and the hook teleports, weee
Yeah I really don't know what to do apart from clicking the one same spot. The fish don't even show up behind Koishi nor is there a catch counter... She must be doing catch-and-release.
But the song's really endearing.
... Koishi has a fishing rod.