You need to talk to Rika in the kitchen in the morning, Lan Shen at the grave in the evening, the Mayor in her office in the morning and Beatrix at her workplace in the morning. Ask them about Riselle and when all 4 answers are answered (can be on different days) go to bed.
If you have a dialog option with a question about Riselle, then everything works. After you talk to each of the 4 girls and go to bed, the story will continue. I will add more information about this quest in the journal.
