Niemon Island is a beautiful island located approximately 200 meters offshore from Futomi in Kamogawa City, Chiba Prefecture. The entire island is formed from sandstone and has a circumference of about 4 kilometers. It is the largest island in Chiba Prefecture and is also the prefecture’s only inhabited island.
The island has a long history and is associated with numerous legends involving historical figures such as Minamoto no Yoritomo and Nichiren. Although the island is privately owned, its scenic and cultural value has been recognized through its designation as a Chiba Prefectural Place of Scenic Beauty and its inclusion among the New 100 Landscapes of Japan.
The island was named after Niemon Hirano, the first head of the family to own the island. In the northern part of the island stands the Hoto Benzaiten Shrine, built during the Edo period (1603–1868). The island was once known as Hoto Island after this shrine.
The eastern part of Niemon Island contains numerous historical remains and natural features. Walking around the island allows visitors to experience the harmony between its long history and its coastal environment.
Niemon Island has been designated as a Chiba Prefectural Place of Scenic Beauty in recognition of its exceptional natural landscape and cultural significance. It is also known as one of the New 100 Landscapes of Japan, making it an important scenic destination in the region.
One of the island’s best-known legends dates back to 1180, when Minamoto no Yoritomo was defeated at the Battle of Ishibashiyama and fled to Awa Province, in what is now southern Chiba.
According to local tradition, Yoritomo was helped by Niemon, the island’s owner at the time, who sheltered him from the pursuing forces of the Taira clan. In gratitude for this assistance, Yoritomo is said to have granted Niemon the surname Hirano and fishing rights in the waters surrounding the island.
Niemon Island is also connected with the Buddhist priest Nichiren. In the eastern part of the island is Kagura-iwa, a rock where Nichiren is said to have watched the rising sun.
Nearby stands Shoichi-i Fukume Inari Daimyojin, a shrine dedicated to the Inari deity. These sites contribute to the island’s distinctive historical and religious atmosphere.
The residence of the Hirano family, who served as successive island owners, was damaged in an earthquake in 1703. It was rebuilt in the center of the island the following year, in 1704.
The building has a history of more than 300 years and is now open to visitors. It provides a glimpse into the lifestyle and history of the family that lived on the island for generations.
Thanks to the warm climate of the southern Boso Peninsula, Niemon Island supports a wide variety of plants throughout the year. Visitors can encounter numerous coastal species as well as plants characteristic of warmer regions.
Among the island’s notable vegetation are kingin-nasubi, isogiku chrysanthemums, and hamakanzo daylilies. Warm-climate plants such as cycads are also found on the island, giving parts of the landscape a distinctly southern Japanese character.
Kagura-iwa is a striking rock associated with the legend of Nichiren, who is said to have stood here and worshipped the rising sun. The rock is one of the island’s most atmospheric historical landmarks.
Minamoto no Yoritomo’s Hidden Cave is traditionally said to be the place where Yoritomo concealed himself while fleeing from the Taira forces. The site offers a tangible connection to one of the island’s most famous legends.
The historic Hirano Family Residence is the former home of the island’s owners. With more than three centuries of history, it is an important cultural feature of Niemon Island and is open to visitors.
Basho-zuka is a memorial mound associated with the famous Edo-period haiku poet Matsuo Basho, adding another layer of Japanese literary history to the island.
Kame-iwa, or “Turtle Rock,” is named for its distinctive shape. Like many of the island’s natural landmarks, it can be enjoyed as part of a leisurely walk around the island.
445 Futomihama, Kamogawa City, Chiba Prefecture
Niemon Island is reached by a traditional ferry boat from the mainland. The crossing itself takes only about five minutes, but the short boat ride adds a special sense of adventure to a visit.
Nearest station: Futomi Station on the JR Uchibo Line, approximately a 12-minute walk from the station.
Boarding point: Futomi Fishing Port
Boat service: Approximately 8:30 a.m. to 5:00 p.m., operating as needed
Admission: Adults 1,350 yen; junior high school students 1,050 yen; elementary school students 950 yen. The fee includes the round-trip boat ride and admission to the island.
Niemon Island has also appeared in Japanese popular culture. The island was featured in the 1971 film Gamera vs. Zigra, where its legends and old-fashioned atmosphere contributed to the setting.
The island is also known as a location associated with Yoshiharu Tsuge’s manga Neji-shiki (“Screw Style”). Some of the locations depicted in the work can still be found on the island today, making it an interesting destination for fans of Japanese manga and cinema.
Niemon Island is a rare destination where visitors can experience history, legends, nature, and traditional island culture in one place. Stories connected with Minamoto no Yoritomo and Nichiren can be discovered alongside historic buildings, unusual rock formations, and rich coastal vegetation.
The journey itself is part of the experience. Crossing the sea by a small ferry from Futomi Fishing Port creates a nostalgic atmosphere and offers a memorable introduction to the island.
For travelers exploring Kamogawa and the southern Boso Peninsula, Niemon Island provides an opportunity to discover a quieter side of Chiba, where centuries-old stories and beautiful coastal scenery remain closely connected.