The Day of Sagittarius can refer to:
- The Day of Sagittarius anime episode
- The Day of Sagittarius (story), a short story in The Rampage of Haruhi Suzumiya
- The Day of Sagittarius III (fictional game), the game within the series
- Day of Sagittarius III (real-life), a portable game based on the fictional one
- The Day of Sagittarius Aftermath manga chapter