Below is a ranking of Japan's 25 fastest marathon women graded relative to their era. The % difference indicated is that between the average of the athlete's 5 fastest performances and the average of the 5 all-time fastest performances at the midpoint of the athlete's career. The third of the athlete's 5 best performances chronologically is used as the midpoint. A % closer to zero indicates a stronger athlete relative to world standard during the athlete's career. Gold indicates a ranking within the top 10 worldwide era-graded rankings, silver indicates top 25, bronze top 50, and green top 100. Click to enlarge.