The Iga Province of Japan is the birthplace of a race of martial arts masters of ninjutsu, known as Shadowmasters. While the true origins of the legendary race of Japanese warriors are shrouded in mystery, Japanese legend states that the Shadowmasters were half human and half demon, and possessed mystical talents. For centuries, the Shadowmasters served as protectors of Iga Province and its people in times of internal strife in feudal Japan.

After the surrender of the Japanese at the end of World War II, U.S. Army Captain James Richards took command, overseeing the government in the Iga province. The mayor of Ueno, a small town in Iga, was Shigeru Ezaki, one of the last of the Shadowmasters who still regularly patrolled and practiced his ninja art. Ezaki's tengu demon mask protected his identity, allowing him the anonymity to practice his art in a post-war Japan where all martial arts were outlawed. Richards and Ezaki became friends following a daring rescue from the path of a driverless Army jeep of Ezaki's son, Saiih, by Richards. Ezaki repaid his debt to Richards by protecting him from a band of renegade Japanese soldiers who had refused surrender. During his battle with the renegades however, Ezaki's tengu mask was knocked off, revealing his identity to both Richards and the escaping renegade leader, Kantaro Umezu. Seeking to stop the renegade activity, and not wanting to arrest his newfound companion, Richards forcibly enlisted Ezaki's aid in tracking down Umezu and his renegades. Endlessly harassed and randomly slain by the ninja, the renegades finally surrendered the violence of the past, appearing to disband, in favor of conquering the world from within.

Over the next decades, the former renegades formed themselves into the Sunrise Society, a group of highly powerful and successful Japanese businessmen, under the direction of Umezu. Ezaki and Richards continued their friendship, and Ezaki began tutoring Richards' son Phillip with his own son Sojin and daughter Yuriko in the art of ninjutsu.

However, after spotting Ezaki in a newspaper photograph, Umezu sought revenge. Umezu killed Richards and kidnapped Ezaki's family hoping to trap the Shadowmaster. Ezaki saved his family, but apparently at the cost of his own life.

Years later, the Sunrise Society again struck at the Ezaki children, sparking them to renew their Shadowmaster training and continue the hunt for their father's killer. Phillip Richards, after leaving for several years to study in America, returned to Japan to join the Ezaki's in their search.

In a final confrontation between the young Shadowmasters and the Sunrise Society, the Ezaki's learned that their father had been held prisoner by the Sunrise Society, and subjected in the years since his "death" to Society cloning experiments.

In recent months, the family of Shadowmasters have crossed paths with the Punisher, assisting him without his knowledge in his war on crime. Most recently, thought, an attaché by the Sunrise Society caused the Punisher to fight alongside the Shadowmasters and the Superhero known as Black Widow. In the ensuing battle, the Shadowmasters defeated the Sunrise Society soldiers, but realized they were unsafe in their present position, thus they fled.

The Shadowmasters fled to Japan in search of a new master to teach them the ninjutsu art of the Shadowmasters. They become the pupils of Hatsu Yakamoto. The Sunrise Society changed its name to the Eternal Sun and still pursued the Shadowmasters when the Punisher came to Japan, at the request of Yakamoto. The Punisher had gone through a training camp with the master's daughter and Yakamoto wanted the Punisher to bring his art of ninjutsu to the United States.

Yuriko, Phillip, and Manzo reintroduced themselves to the Punisher after he recognized them as the people he had helped on the streets of New York. Kathryn Yakamoto was also there. The Shadowmasters planned an attack on the new Eternal Sun base complex.

The local officer of the Eternal Sun turned out to be Iris Green, a nurse whose trail the Punisher had been following for a long time. The Shadowmasters infiltrated the headquarters in order to destroy their records and inflict as much damage as possible-- they blew the whole complex up. In retaliation, the Eternal Sun assassinated the elder Yakamoto.

The Punisher and Kathryn followed Iris Green to the U.S., but the Shadowmasters stayed in Japan to continue their fight against their fathers' killers.