"To become a Japanese citizen, a foreigner must display 'good conduct', among other things. The rules do not specify what that means, and make no mention of living wafu (Japanese-style). But for one candidate, at least, it involved officials looking in his fridge and inspecting his children’s toys to see if he was Japanese enough (he was). Bureaucratic discretion is the main reason why it is hard to get Japanese nationality. The ministry of justice, which handles the process, says officials may visit applicants’ homes and talk to their neighbors."
Via Seth Dixon