The Emperor of Japan appears in Gulliver's Travels in III part when he returns from Luggnagg with a letter of recommendation from Luggnaggnian king to help him sail back to his country. When he reaches Japan he presents the letter recommendation to the custom house official who takes him to the emperor. He introduces himself as a Dutch shipwreck who was stranded on an isolated island and requests to arrange to send him on board to Nangasac as many traders from his country came to japan. The emperor consents to help in in VIEW of the honor of the Luggnaggnian king. However, when Gulliver requested him to exempt him from the custom imposed on his countrymen  i.e. trampling the crucifix as he had happened to go there due to his MISFORTUNE and not for trade. The emperor was surprised as he felt none of his countrymen had ever made this request. He doubts if he was a Christian. Nevertheless, he grants his request considering the favor to Luggnaggnian king and instructs him that he has manage the whole affair with dexterity and his officers should be commanded to let Gulliver pass as it were by MISTAKE, for he feared that if his countrymen cam to know about it, they WOULD kill him.

The emperor of Japan proves his majestic mindset and diplomacy to the reader.