Okunoshima, an island in the Seto Inland Sea, is known as a "rabbit island" for being inhabited by around 500 to 600 wild rabbits. Despite this current image, the island has a dark past.

The tiny island, located in the city of Takehara, Hiroshima Prefecture, hosted a poison gas plant of the now-defunct Imperial Japanese Army before and during World War II, leading to its removal from the map for confidentiality purposes.

Masayuki Yamauchi, an 80-year-old former high school teacher, has continued to tell the island's history for about 30 years, calling for attention to be paid to Japan's history of aggression, not just its damage from the war, such as the 1945 atomic bombing of Hiroshima.