A friend sent me the image, following a request on Facebook. First record of S. atrorubens away from Fijis Northern region I believe (no other accurate records on GBIF in any case) - therefore of interest.
Helice tridens
アシハラガニ
Yoshino River Estuary, Tokushima, Japan
吉野川河口干潟、徳島県
Small crab I found in a river near the Sahio-ji in Kyoto