HX-9 I is a Mars-like planet in the HX-9 System notable for its highly toxic atmosphere and extremely high metal content. HX-9 I has one large moon.

The world is known to hold a rich treasure of metals in its core, in a mantle of uranium and Thorium with traces of Nickel, Cobalt, Chromium, Zinc, Molybdenum, Vanadium, and Manganese, and for a thin crust of Nickel, Zinc, and Molybdenum with trace concentrations of Gold and Silver. Some of the higher-level ores have been mined, and the low-level ores are still available.

In addition to the old mining facilities and underground shafts, the Star Army of Yamatai created a secret underground storage depot with enough supplies to restock a small fleet of starships in the event that the normal fleet depots were compromised. The existence of this facility was not recorded in any electronic format and all the engineers who built it were voluntarily killed and brought back from prior backups so they have no knowledge of the assignment. The depot's location was only written in sealed envelopes placed in a locker in the captain's cabin of selected Star Army of Yamatai battleships, to be opened only in dire circumstances.

• Type Large iron/silicate
• Radius 7883.95 km (1.24 x earth)
• Surface Area 7.81 x 10⁸ km²
• Land Area 7.89 x 10⁸ km² (5.30 x earth)
• Mass 1.24 x 10²⁵ kg (2.08 x earth)
• Density 6.04 g/cm³ (1.10 x earth)
• Composition 50.0% iron, 19.0% oxygen, 17.6% silicon, 8.3% titanium, 5.1% other metals, trace other elements

• Gravity 13.26 m/s² (1.36 x earth)
• Escape Velocity 14.46 km/s
• Rotation
• Period 33.03 hours
• Axis Tilt 57.48 °

• Water 0 %
• Ice 4 %

• Type Dense toxic
• Pressure 167.92 kPa (1.66 x earth)
• Composition 81.7% sulfur dioxide, 18.3% nitrogen, trace other gases

• Type Standard
• Min Temp 263 K (-10 °C)
• Avg Temp 298 K (25 °C)
• Max Temp 355 K (82 °C)

• Large moon