The Global Precipitation Measurement (GPM) Core Observatory was launched from Tanegashima Space Center JAPAN on Feb 28 (JST), and the initial on-orbit check-out of all instruments onboard the Core Observatory has been completed. Along with the completion of the initial checkout, the GPM ground systems have been operational in both of NASA and JAXA. JAXA Mission Operations System Office has been developing GPM Mission Operation System (GPM-MOS) and data distribution system named as G-Portal toward the coming GPM data release. In this paper, we show overview of GPM-MOS and G-Portal service. Next, we show that data distribution time, latency of observation data, has been successfully confirmed to meet the system requirements. In consequence, utilization efficiency for end users will be considerably improved compared with the Tropical Rainfall Measuring Mission (TRMM) era.