For the past few years, the Osaka Pharmaceutical Association has printed and distributed pamphlets depicting Inagaki, crossing her arms in an "X", the Japanese symbol for "no" or "bad", and the catchphrase: "No good, absolutely. Cannabis." ("Dame, zettai. Taima." or ダメ、ゼッタイ. 大麻.) There is also a website, which gives info about various illegal drugs.
The pamphlets are public service announcements, and they are distributed in hospitals, government buildings, and pharmacies. Last fall, a new campaign was launched that focused on "dappou herbs", which are synthetic drugs that have become an issue in the last year—perhaps more so than marijuana.
Marijuana use is more accepted in the West than in Japan. While in recent years, the U.S. has taken a far more progressive attitude towards marijuana, recognizing its medicinal properties, Japan has not and has some of the toughest laws in the world against the drug. Ironically, Japan's strict anti-marijuana laws were imposed by the U.S. after World War II, Japan Today points out. The drug is very much stigmatized in the country, and if Japanese celebrities are caught with pot, it can end their career.
Inagaki has always been a fascinating comedian, because her entire schtick is partly based on her cosplaying. She wasn't a cosplayer at first, but was asked to create an act for otaku (geeks). She appears on Osaka TV show Rokemitsu, dressed as Langley.
In the past, Inagaki has often gone to the Japanese countryside (she's now going through Europe), where she obviously stands out. At the most base level, the gag is that she's a fish out of water. Most locals don't quite know what to make of her, nor do they get the Eva inside jokes!
Having her appear in an anti-drug campaign is incredibly post modern: she isn't Asuka Langley, but a cosplaying comedian dressed as Langley, who doesn't want you to smoke illicit substances. The target of the campaign is young people who might smoke marijuana or other herbs. If they don't know Inagaki, they might know Eva. If they know Evangelion, they might smoke marijuana. KIDDING. (Well, sorta.)
Inagaki's continued inclusion in the campaign is a testament to her own popularity in Osaka as well as the geek power of Evangelion and Evangelion cosplay.