Japan has successfully eradicated invasive small Indian mongooses from Amami Oshima Island, a UNESCO World Heritage site. Originally introduced in 1979 to control habu snakes, the mongooses themselves became a problem, disrupting the island’s delicate ecosystem. Decades of intensive trapping, tracking, and monitoring culminated in their complete removal. This marks one of the largest mongoose eradication programs globally, demonstrating a significant win for conservation efforts. The successful removal paves the way for the recovery of native wildlife populations previously threatened by the invasive species. The project highlights Japan’s commitment to ecological restoration and protecting its unique biodiversity. This achievement offers valuable lessons for managing invasive species worldwide.