I loaded previous save to get a refresher on how this happens. After the shower scene, you buy the monster bait and enter Forest in Afternoon to trigger a meeting with Karyn. This is written in the first "hint" as well. After that, you unlock the pond area, where the followup is to bring 2x monster bait in the morning, and so on. IF, for some reason, you cant do this, then you might have an outdated version of the game, as Karyn story is one of the latest additions. Cant think of any other reason why you cant progress otherwise. There is a link to Karyn progress that is linked to Yumeko too, but I believe that is later.