Do not ever try to bring marijuana in any form into Japan. Former WWE Superstar Evan Bourne, now known as Matt Sydal in his time in New Japan Pro Wrestling has had to learn that lesson the hard way.
In the latest edition of the Wrestling Observer Newsletter, Dave Meltzer wrote that Matt Sydal is expected to be released from a prison in Osaka, Japan on December 6th. Sydal was caught trying to sneak liquid cannabis into the country at the Osaka International Airport back in September. He was held in a regional jail in Osaka for a month and in October, he went to court and pled guilty to possession of Marijuana. The prosecutor had asked for either 18 months in jail or 3 years probation and Sydal accepted the probation deal. A ruling on his release date is expected sometime next week.
Sydal's sentence could be considered quite lenient, since the average Japanese citizen can spend up to 5 years in prison for a possession conviction. It's unknown whether or not anyone in the New Japan office helped Sydal with his legal troubles.
At this point details are unclear about Sydal's banishment from Japan. It could be a lifetime ban or just three years. Several high level celebrities have been banned for life just from drug convictions in their own country; people such as Paris Hilton, Russell Brand and others have not been allowed into the country as a result of drug-based offenses. The most famous case of a foreigner being caught with marijuana in Japan is when Sir Paul McCartney was caught trying to bring half a pound of it into Narita Airport in Tokyo in January of 1980. He spent 9 days in jail before being sent home.