| Sai | |
|---|---|
 Sai, as he appears in Rei Gaiden. | |
| Name in Kanji | サイ |
| Name in Romaji | Sai |
| Family | Mari (younger sister) |
| Position(s) | Orphan boy |
| Appearances | Rei Gaiden |
- Sai (サイ Sai)
- Appearing in the first Rei Gaiden one-shot, Sai is a young boy whose parents were killed by bandits. They also kidnapped his little sister, Mari. He meets Rei on his journey for revenge but collapses due to injury. Sympathizing with the boy, Rei takes revenge for him and reunites him with his sister.