Pia is one of the bachelorettes in Rune Factory 3. A mermaid, she used to live in the ocean, but was "adopted" by Shinonome. On rainy days she can be seen in her mermaid form.
Bulletin Board Quests
To complete this quest you need to complete Pia's bath "census" by answering her three questions. She first asks what temperature you prefer the baths to be.