To determine the Prime Minister of Fiji:
1. Sitiveni Rabuka was sworn in as the Prime Minister of Fiji in December 2022.
2. He previously served as Prime Minister from 1992 to 1999.
3. The other options are leaders of different countries: Rishi Sunak (UK), Fumio Kishida (Japan), and Pedro Sánchez (Spain).
Therefore, the correct answer is (1) Sitiveni Rabuka.