This paper presents the results of a drone-based airborne LiDAR survey of the Tottori-kamitakatsuka mounded tomb located in Akaiwa city, Okayama prefecture. Dating to the second half of the Late Kofun period (latter 6th century), this mounded tomb has traditionally been considered either the largest keyhole-shaped mounded tomb in the Bizen area of this period (total length of either 67 m or 75 m) or a round tomb with a diameter of approximately 30 m. Details of the tomb’s size and shape have long been uncertain, owing to the lack of detailed survey mapping of the mound and its environs. In this paper, the authors present their findings on the shape and size of the mounded tomb based on high-quality three-dimensional data acquired through airborne LiDAR survey utilizing a drone; they suggest that the tomb is a keyhole-shaped mounded tomb measuring approximately 75 m in length. This mounded tomb is therefore the second largest mounded tomb of the Kibi region during the period, following the Kōmorizuka mounded tomb located in Sōja city. Additionally, the authors discuss the significance such three-dimensional data has for enhancing our understanding of Japanese history on both a local and archipelago-wide scale.