I kinda like Tokiko/Rinnosuke better. Sakuya/Rinnosuke causes a lot of complications (most notably either she would never see him due to Remi, or Remi would get angry because she's seeing him and not working), and also Tokiko/Rinnosuke would just be really cute. Plus, they're both pretty equivalent in terms of power. Sakuya would be kind of frightening when mad.