| 1. | The famous writer Nagai Kafu was his half-brother. Le célèbre écrivain Nagai Kafu est son demi-frère. |
| 2. | His son Shunta Nagai is also a former footballer. Son fils Shunta Nagai est également footballeur. |
| 3. | Darth Nihl is a Nagai. Dark Nihl est un Nagai. |
| 4. | Nagai Yume (長い夢, lit. De longs rêves (长い梦, Nagai Yume?) |
| 5. | His real name was Kiyoto Nagai (永井 清人 Nagai Kiyoto). Son vrai nom est Kiyoto Nagai (永井清人, Nagai Kiyoto?). |
| 6. | His real name was Kiyoto Nagai (永井 清人 Nagai Kiyoto). Son vrai nom est Kiyoto Nagai (永井清人, Nagai Kiyoto?). |
| 7. | Nagai became a member of the Japan Art Academy in 1968. Nagai est membre de l'Académie japonaise des arts en 1968. |
| 8. | His son Naohira succeeded to the family headship. Son fils Nagai Naohira lui succède à la tête de la famille. |
| 9. | In 1981, Nagai was awarded the Order of Culture by the Japanese government. En 1981, Nagai est décoré de l'Ordre de la Culture. |
| 10. | His son Nagai Naohiro also became a high-ranking shogunate official. Son fils Nagai Naohiro est également un officiel de haut rang du shogunat. |