Tokyo Metro Co., Ltd. (“Tokyo Metro”) operates a subway network with nine lines, 195.1 km of track and daily ridership of 6.44 million in Tokyo, the largest metropolitan area in the world. More than 80 years have passed since some tunnels were built, and soft ground, saline groundwater and other factors have caused peculiar structural deformations. In this paper, we describe the use of IT for efficient tunnel inspections, and the use of neutralization projections and a visualization tool in efforts toward drafting optimal repair plans for water leakage.