Reimu did enjoy eating the berries, and wanted to get more, but decided against it for now.  She remembered Jonna mentioning an alchemist that lived by the lake.  Her sword was still missing, and Jonna had cautioned her against visiting the merfolk for now, but this alchemist might know more about the lake than Jonna did - after all, the old guardsman was living in a sheltered town, not out in the open.  Grabbing her backpack again, she headed off towards the lake, in search of this alchemist.