Personally, I was held overnight in a cell in KIX (Osaka International Airport) because after 6 hours of back and forth interviews, I couldn't provide a convincing enough reason for working for a Japanese company (my own company) without the correct visa. This was entirely due to miscommunication but something that would have been obvious – and easily remedied – had I consulted the right people. Fortunately, I was granted conditional entry the following morning. Though despite the inconvenience, the officers and warden were extremely pleasant and very accommodating.