The central premise of the series is a biological anomaly: for hundreds of years, the women of Ushiha have been able to carry and deliver a child in just one week. However, the island's fertility is in decline due to a genetic deterioration among the local male population. Seiichi, possessing a high libido and the necessary genetic diversity, is recruited to serve as the island's primary inseminator to ensure the population's survival. Production and Availability
As of 2025, a verified, unopened digital key for the exclusive sells for upwards of $800 on private Japanese auction forums. koumijima shuu 7 de umeru mesutachi exclusive
Given the extreme rarity of the many fans have turned to: The central premise of the series is a