I visited Myōken-jima as part of my island-hopping. It’s said to be the only natural island in Tokyo’s 23 wards (though this is debated). A narrow island in the old Edogawa River, in Higashi-Kasai, Edogawa Ward. I’ve passed nearby countless times on the Tōzai Line but had never stopped by. It’s the kind of island you won’t visit unless you deliberately decide to.
Myōken-jima
A small island roughly 700 m north-south and 200 m east-west. Originally formed naturally as a sandbar in the old Edogawa River. From the Meiji era onward, it was developed as factory land, and most of the island is still occupied by factories and businesses today. It’s not a tourist destination, and few people visit.
Accessible on foot via a bridge — no boat needed.
Access
About a 10-minute walk from Urayasu Station on the Tokyo Metro Tōzai Line. Head west from the station to reach the old Edogawa River. There’s a ramp from the bridge down to the island, accessible to pedestrians.
The Island
The island is an industrial zone filled with warehouses, trucks, and containers. Few people were around. At the entrance, there’s a faded island guide map — one of the few signs that this place is an “island.” The old Edogawa flowing between the island and the mainland is narrow, so it doesn’t feel much like being on an island.
I stayed 5–10 minutes, walking through the island to see it all, then walked to Kasai Station. You could go back to Urayasu Station, but Kasai Station is also reachable in 10–15 minutes walking north along the old Edogawa.