Heart of a Samurai is a 2010 novel by Margi Preus chronicling the real-life Japanese adventurer Manjiro Nakahama, called “the boy who discovered America.” Set in the mid-1800s, this middle-grade novel depicts Manjiro's shipwreck, exploration of the whaling industry and America, and eventual return to Japan, where he works with the shogunate to end Japanese isolationism and finally achieve his dream of becoming a samurai. Manjiro's curiosity enables him to overcome his initial fears about the world outside Japan, yet many people refuse to do the same for him, highlighting the theme of The Conditions for Inter-Cultural Understanding. The book won a Newbery Medal and several other awards. Margi Preus is a prolific children’s author who primarily writes historical fiction, action, and mystery novels; while not Japanese, Preus often writes stories with Japanese protagonists. The novel has elements of a Bildungsroman incorporated into its primary genre of historical fiction.

This guide uses the Amulet Books paperback edition, published in 2012.

Content Warning: The source material depicts cultural stereotypes and biases from the era it is set, including racially motivated attempted violence.

Plot Summary

In 1841, Manjiro and four fellow fishermen—Denzo, Jusuke, Goemon, and Toraemon—are fishing off the Japanese coast. Manjiro notices an oncoming storm, which his shipmates ignore until it destroys their sail and rudder, stranding them in the Pacific. The fishermen drift without hope of rescue and discuss their dreams; Manjiro wants to become a samurai, a vain ambition for a peasant. They are afraid of landing in another country because Japan’s isolationist laws forbid reentry.

Eventually, the fishermen land on an island covered in albatrosses. The birds depart, however, leaving them without a food source. Goemon and Manjiro declare themselves the samurai of Bird Island; soon after, they find graves, showing that others were wrecked on the island. As the fishermen grow weak and delirious, Manjiro sees a boat in the distance and swims to it.

The ship, the John Howland, is a whaling vessel. The appearance of the crew, who are primarily white Americans, alarms the Japanese fishermen. Both groups struggle to communicate through linguistic and cultural barriers. The crew on the John Howland gives them refuge and care, but all except Manjiro are wary. The ship's captain, Whitfield, encourages Manjiro to ask questions; he is kinder than many of the sailors, although he still demands that Manjiro adopt Western customs. Captain Whitfield explains to Manjiro that he cannot return him home due to Japan's isolationist policies. They begin to bond over their mutual loneliness and separation from their families.

Manjiro aids the crew in taking a sperm whale, although the process horrifies him as he is a Buddhist. He watches them dismember the whale for parts. An unpleasant whaler with racist attitudes, Jolly, mistreats him and calls him derogatory terms, to the displeasure of the rest of the crew. Captain Whitfield renames Manjiro “John Mung” to integrate him with the sailors. Manjiro's countrymen warn him that he is being corrupted. Regardless, he continues to learn English and how to thrive on the ship.

Eventually, they land in Honolulu. The other fishermen stay, hoping to take a ship back to Japan, but Whitfield requests that Manjiro remain, asking him to be his son. Manjiro agrees, wanting to see the world. Before he can leave, Jolly and some other men assault him and Goemon, robbing them and threatening to frame Manjiro for Jolly’s theft of the captain's pocket watch. Manjiro fends them off and escapes with the watch. Back at sea, Manjiro discovers that the crew left Jolly in Honolulu. Preparing to give the watch back to the captain, he accidentally drops it into the sea. In fact, it falls into a lifeboat, and the whalers later prank Manjiro by pretending to find the watch in a whale’s corpse. He confesses the "crime" to the captain, who laughs and reassures him that he did nothing wrong.

Eventually, the John Howland returns to Massachusetts. Manjiro explores the strange land, but local boys mock him for his race. The captain's home is in disarray, so they stay with a nearby family, the Akens instead. Whitfield marries Albertina, a woman from New York, who develops a fond relationship with Manjiro. The new family runs a farm, and Manjiro continues to adapt. He befriends a boy named Terry and goes to school but faces discrimination at church and from a classmate, Tom. He challenges Tom to a horse race, which he loses; at the same time, Whitfield announces he is going back to sea. Although lonely, Manjiro's attachments keep him happy—to a baby brother, William Henry, and a girl, Catherine.

Manjiro becomes an apprentice but soon grows sick and returns home. In 1846, Mr. Davis, a former crewmate on the John Howland, asks him to return to sea as a steward—a low position for Manjiro's qualifications. He agrees, wanting to see more of the world and go home to Japan. On the ship, he reunites with a subdued, aged Jolly, who warns him to disembark while he can.

On the voyage, Manjiro runs into Japanese fishermen who do not speak his dialect and refuse to take him home. Davis accuses him of desertion and threatens his life. The ship catches no whales, and Davis grows increasingly unstable. Manjiro catches a sea turtle with his bare hands, earning the praise of the crew. Soon, the crew mutinies against Davis, whose behavior has become violent and unpredictable, and they promote Manjiro to harpooner. Manjiro brings a parrot from Singapore home to William Henry but discovers the boy died while he was away. He and Terry leave for the California Gold Rush. Manjiro finds enough gold to get him and his Japanese friends home.

Manjiro, Goemon, and Denzo return to Japan, but Japanese officials promptly arrest them. The government imprisons and interrogates them. After two years, Manjiro returns home to his mother but soon is informed that he will become a samurai and teach young samurai English. An epilogue describes Manjiro's efforts to end Japanese isolationism and his other exploits as a samurai and an interpreter.