Tonton Streaming The Time Tunnel (1966) S1E17 - Kill Two by Two

The guys land on an island in the South Pacific at the tail end of WW2. Two Japanese soldiers are holding it against invasion: the deranged Lt. Nakamura, who hates Americans, and the loyal sergeant, Itsugi. Nakamura soon fixates on the travellers, and forces them into a series of sadistic games. When the Project: TickTock staff call in a consultant to try and get a fix on the guys' location, the consultant turns out to be the lieutenant's father. Apparently Nakamura disappeared during the War and now his father wants them to recover his son. Tony and Doug manage to turn the tables on Nakamura and warn the advancing fleet. The young Nakamura, a failed kamikaze pilot, finally decides to end his life with honor by seppuku, as his father looks on through the portal.