Sunlight Castle was a luxury retirement home housed in a former Meiji era bank edifice in Yokohama's Isezakicho district. Ryuhei Hoshino and his Seiryu-kai yakuza clan bought the historic building in the 1980s and turned it into a retirement home directed by Yamano Totsuka. Totsuka created an elaborate healthcare and pension scam; residents would need to pay ¥5,000,000 upfront before making monthly payments of ¥500,000. People seeking to be taken to the "Excellent Area" needed to pay ¥20,000,000 initially and ¥1,000,000 monthly after being screened for certain qualifications. The yakuza secretly euthanized Excellent Room residents, kept their deaths secret, and continued to collect their pension payments. In 2019, Ichiban Kasuga and his friends infiltrated the castle through Hello Work at the behest of Otohime Land owner Isao Nonomiya, saving the father of one of his employees and exposing the scam to Seiryu-kai Ryuhei Hoshino. Hoshino disapproved of Totsuka's highly immoral activities and exiled him from the family, and the Seiryu Clan proceeded to close down the care home.