Japanese Officers in WWII fairly commonly carried Katana's with them into battle as a symbol of them being a part of the officer class. While their exploits are not on the same level as Mad Jack Churchill there are a few note worthy actions. The one in particular action I can name is from the Malayan Campaign.

During the Battle of Slim River, Lt. Watanabe led his tank platoon as part of the spearhead that penetrated the British defense in depth and drove to capture the Slim River Bridge that was being rigged for detonation. He was confronted by 2 40mm Bofors emplacements of the Singapore and Hong Kong Volunteer Artillery Regiment which he caused to flee as they could not penetrate the armour of his tank. They had however stalled the advance long enough for bridge to be potentially detonated, destroying him and this unit in the process. Lt. Watanabe leaped out of his tank and used his Katana to cut the wires to the demolition charges thus securing the bridge and preventing its destruction which would have stalled the Japanese advance.

While perhaps not as illustrious or as dramatic as Mad Jack who ambushed and killed people on multiple occasions using such archaic weapons, this was an instance where it was used for some significance. Although wire cutters could have done the job, the bridge was at risk of being eminently destroyed and his sword could have been the tool that adverted that eventuality as it allowed him to immediately cut the wires. More importantly, this account is corroborated by Japanese and British sources (although to a lesser degree) so it is generally looked upon to be reliable and factual.

Sources:

Singapore Burning: Heroism and Surrender in WWII - Colin Smith

Japan's Greatest Victory, Britain's Worse Defeat - Col. Masanobu Tsuji