|Orbital Distance||15.68 AU|
|Orbital Period||47.8 Earth Years|
|Day Length||27.6 Earth Hours|
|Atm. Pressure||0.95 atm|
|Surface Temp||46 °C|
|Surface Gravity||0.8 g|
|Mass||0.679 Earth Masses|
|Colony Founded||2166 CE|
An atmosphere similar to Earth's made Intai'sei an early candidate for human colonization. However, prohibitively high temperatures and an arid climate have proven a hindrance to terraforming and agriculture. A few human cities were founded, but the majority of the human population on Intai'sei remains scattered across the vast deserts, operating wind farms and geological research stations.
- Mission: Citadel: Kakliosaur Fossil
- Assignment: Pinnacle Station: Convoy
- In Pinnacle Station, completing Admiral Ahern's special simulator scenario in the mission Pinnacle Station: Combat Missions grants access to Ahern's retirement home on Intai'sei.
- Intai'sei's orbital period is 47.8 Earth years, whereas its neighbouring planet has an orbital period of 94.5 Earth years, making it unlikely to be the fifth planet of the Phoenix system. Its orbital period in Mass Effect suggests a location in between Tuntau and Sylsalto, at a distance of nearly 16 AU from the star Phoenix. This discrepancy is corrected in Mass Effect 3, and Intai'sei is moved from the fifth orbital of the system to the third.
- The name for the planet may be taken from the Japanese noun "intaiseikatsu" (隠退生活) which means "secluded life."
- Intai'sei can also be conveniently read in Japanese as 引退星 ("retirement planet").