Under oak. Seemed too small for stag beetle. Could it be C. scopolii? There was one flying around very close but it was sitting outside of my shooting range.
A prominent scientific name, Carabus insulicola insulicola Chaudoir, 1869
Temperature: 24 degrees celsius (76 degrees fahrenheit)
LOC: Japan, Kanto Region, Tokyo, Hachioji City, Mt. Takao 439 m