The 5th leg of the Hakone Ekiden has undergone three major course changes since 2006, fragmenting the record books across four incompatible eras. No official cross-era equivalence exists, and cross-era comparisons are often crowded with misinformation and speculation. This report develops a nearest-split interpolation method using each runner's own checkpoint timing data to produce comparable times on the current 20.8km course. The aim is not to provide a definitive ranking, but to clarify the historical record and facilitate informed discussion about the legendary 'Mountain Gods' of the Hakone Ekiden.
An English version of the report will be uploaded in the next update.