The 2016 Kumamoto earthquake sequence produced extensive surface ruptures not only along the Futagawa section of the Futagawa fault zone and the Takano-Shirahata section of the Hinagu fault zone, but along the Kita-amagi fault comprising the Uto section of the Futagawa fault zone. Although a large number of researches on paleoseismology have been carried out on the Futagawa section and the Takano-Shirahata section so far, no paleoseismic investigations have taken place on the Uto section. In order to unravel recent behavior of the Kita-amagi fault, including the 2016 earthquake, we performed detailed topographic survey and paleoseismic trenching of the southern trace of the Kita-amagi fault that bounds the northwestern margin of the Kita-amagi Uplands. A 20-cm-grid high resolution DEM (digital elevation model) and topographic profiles, both of which are based on total station survey, allowed us to document morphological features of the surface rupture zone in greater detail regardless of its slight horizontal and vertical displacements. A paleoseismic trench at a site immediately adjacent to the surface rupture exposed no clear evidence for the 2016 earthquake except for the ambiguous, small near-surface fissures. On the contrary, unlike the 2016 earthquake, evidence for a paleoseismic event with a distinct deformation of strata, whose structural relief is consistent with the long-term tectonic landform, was identified. Although the age of this event horizon was poorly constrained and number of events within the horizon could not be determined, at least one event that contributed the topographic development occurred sometime after ～16,000 cal BP but before ～3,000 cal BP or ～10,000 cal BP (after ～17,000 cal BP but before ～2,000 cal BP or ～9,000 cal BP, taking into account the possibility that the 14C ages of the organic sediments bracketing the event timing could be 1,000 years older or younger at the maximum than their actual depositional ages).
