sentences:  The Nigerian mafia in Tokyo engages in heroin dealing with the "yakuza", the prostitution of Filipino women, money laundering, car theft and arranging fake marriages, amongst other crimes.Following a number of incidents at Nigerian-owned bars in which patrons were drugged and robbed, the United States embassy in Japan issued a warning to US citizens to avoid certain bars and clubs in Roppongi.Crimes committed by Nigerians are largely overlooked by Japanese police due to fear of being labelled racist by the Nigerian embassy which could cause a diplomatic incident.