Zangetsu is one of the Eblan Four in Final Fantasy IV: The After Years, and is known as Zangetsu of Thunder. He is an elderly man with aspirations of becoming a shinobi, despite being a late bloomer, and admires Edge, who looks young enough to be his son, as his master.
When Eblan receives word of Baron stealing Crystals from other nations, the Eblan Four become eager to assist Edge, and are sent on missions to gather information. Zangetsu disguises himself as a dwarf to freely roam King Giott's castle, and after confirming the Dark Crystal is still safe and the Tower of Babil is reactivated, he returns to the surface via a secret tunnel near the castle.
After the mission is completed, Zangetsu returns to Eblan by walking across the sea. He reunites with Edge and the other Eblan Four within the Tower of Babil and after being forced to escape from the Mysterious Girl and Ifrit they fall to the Underworld and into the Falcon.
In the Gathering Tale, Zangetsu watches over Porom and the other incapacitated characters below the deck of Falcon. During the ending, he is seen as a dwarf as Luca upgrades the Falcon. Zangetsu and the other Ninja Guard of Eblan renew their vows of loyalty to Edge awaiting for their next mission.