Sayoko Uehara is the Nurse that works in the local Hospital. Getting a Job at the Hospital and building your courage will allow you to meet her and establish the Devil social link. She tempts you out of boredom from her job. Deny her advances and act innocent to boost the Nurse / Devil social link.
The Nurse Social Link or the Devil Arcana can be established as early as 5/25 by working at the hospital Wednesday, Thursday, or Friday nights.