IGS (Information Gathering Satellites) were Japan's first military reconnaissance satellites. Many details, including orbital parameters, were classified for the first time in Japan's post-war history. The satellites, called Optical-1 and Radar-1, carried either optical or synthetic aperture radar sensors. NASDA reported that deployment of each satellite's solar panels went as planned and that the spacecrafts' operations were nominal. Full information and transmissions services of the IGS system were expected to begin in March 2004 following the planned launch in August 2003 of Optical-2 and Radar-2. The design life of the satellites was five years.

A primary mission for the satellites was the monitoring of North Korea. Repeated testing of North Korea's Taepo Dong missiles, some of them overflying Japanese territory, provided the political impetus for the project.

Japan spent about 250 billion yen ($2.2 billion) on the IGS program up to the first launch and expected to spend 40 billion yen per year thereafter. The price of each spacecraft was believed to be about 50 billion yen. Another 50 billion yen was spent on the command, control and communications ground station.

• 2003 March 28 - IGS-1b - Launch Site: Tanegashima. Launch Complex: Y. Launch Vehicle: H-2. Mass: 1,200 kg (2,600 lb). Perigee: 489 km (303 mi). Apogee: 500 km (310 mi). Inclination: 97.30 deg. Period: 94.20 min.
  Radar satellite.

• 2003 March 28 - IGS-1a - Launch Site: Tanegashima. Launch Complex: Y. Launch Vehicle: H-2. Mass: 850 kg (1,870 lb). Perigee: 483 km (300 mi). Apogee: 495 km (307 mi). Inclination: 97.30 deg. Period: 94.20 min.
  Optical reconnaisance satellite. First Japanese military space mission. Dual payload. Delayed from February 2003. The Tanegashima facility was under strict security, guarded by 400 police officers wearing bullet-proof vests. Waters near the pad were patrolled by the coast guard.

• 2003 November 29 - IGS-2b - Launch Site: Tanegashima. Launch Complex: Y. Launch Vehicle: H-2. FAILURE: Destroyed by range safety after solid booster nozzle burn-through resulted in motor not separating from core. Mass: 1,200 kg (2,600 lb).
  

• 2003 November 29 - IGS-2a - Launch Site: Tanegashima. Launch Complex: Y. Launch Vehicle: H-2. FAILURE: Destroyed by range safety after solid booster nozzle burn-through resulted in motor not separating from core. Mass: 850 kg (1,870 lb).
  The launch failure meant that Japan's planned intelligence satellite constellation was crippled. The system was already in trouble due to the reported poor performance of the first two elements launched.

• 2006 September 11 - IGS-3A - Launch Site: Tanegashima. Launch Complex: Y. Launch Vehicle: H-2. Mass: 850 kg (1,870 lb). Perigee: 484 km (300 mi). Apogee: 491 km (305 mi). Inclination: 97.30 deg.
  Information Gathering Satellite / Optical-2 military surveillance satellite, launched to replace IGS O-1 launched in 2003, which demonstrated technical problems. The first replacement, IGS-O-2, was lost in a launch failure in 2003.

• 2007 February 24 - IGS-2 - Launch Site: Tanegashima. Launch Complex: Y. Launch Vehicle: H-2. Mass: 1,200 kg (2,600 lb).
  Information Gathering Satellite Radar-2. Japanese military satellite using a synthetic aperture radar for all-weather, 24-hour, high-resolution surveillance of the earth.

• 2007 February 24 - IGS-3V - Launch Site: Tanegashima. Launch Complex: Y. Launch Vehicle: H-2. Mass: 850 kg (1,870 lb).
  Optical-3 Verification Satellite, an experimental satellite on a six-month mission to test payloads planned for the Optical-3 second-generation Japanese military optical surveillance satellite. The production-type Optical-3 satellite was expected to launch in 2009.