The study shows the use of Normalized Difference Moisture Index (NDMI) acquired by the Sentinel 2A in evaluating the trees crowns damage in Japan largest wildfire in 2017. Ground truth used was from field-collected data on scorch crowns of trees from the burned area. Our results show that difference NDMI (dNDMI) of pre and post-fire images was the best spectral index among Normalize Burn Ratio (NBR), NBR2, Normalize Difference Vegetation Index (NDVI), difference NBR (dNBR), difference NBR2 (dNBR2) and difference NDVI (dNDVI) for spectral sensitivity in differentiating unburned and burned areas. The estimates area for tree crowns damage due to high severity was the largest at 147 hectares (33.1%) and the total calculated burned area was 445.02 hectares which exceed less than 8% of the total burned area reported. This study is needed for Japan because of the different ecosystem and climate with other fire studies conducted in different regions.