Etymology and production
Baijiu is a clear drink usually distilled from sorghum, although sometimes other grains may be used; baijiu varieties produced in southern China are typically made from glutinous rice, while those from northern China are generally made of sorghum, wheat, barley, millet, or occasionally Job's tears.
The japanese translation is パイチュウ (Paichuu).
 Appearance in DC
Baijiu appears in Volume 10/File 2/Page 9 (File 92, Heiji's introduction) and Volume 24/File 10/Page 9 (File 241, Haibara in Haido City Hotel) as 白乾児 (pronounced パイカル, or Paikaru). A clearer picture of the bottle exists on Volume 10/File 6/Page 9, where the English "Bai Ganr" is barely legible above the Japanese.
 Speculation about the origins of the alcohol
The label on the bottle is written in a mixture of Japanese and Chinese:
- 白乾児 is Japanese; In Chinese it would be 白乾兒 in traditional, 白干儿 in simplified
- 古法乾式 is not standard Chinese, roughly means "traditionally-made dry-type"
- 芳香千里 however IS a Chinese phrase in common use, meaning roughly "renowned for its taste"
This strongly suggests the bottle was imported by a Japanese company, vs. the alcohol having come directly from China through other means.
 APTX antidote
The baijiu gave Conan and Haibara a limited time (maybe 15 to 30 minutes) reversion to adult form. Unlike Haibara's later temporary antidotes, the baijiu took a considerable time before it began to work, and only then after making their respective colds much worse. The transformation and reversion are heralded by repeated bouts of sharp chest pain centered over the heart which become more frequent as the transformation draws near. In the short time Conan and Haibara were in their adult forms, they were unwell, sweating, and breathing heavily. After the reversion back to child form, both Conan and Haibara seemed more taxed and ill than they started.
The baijiu antidote seems to be one time use only, as Haibara says that the body builds a resistance to the baijiu that makes it no longer work. Additionally, it may only work when the drinker is sick and thus has a weakened immune system as both Conan and Haibara used it while sick with colds. Haibara speculated there was some enzyme in the baijiu which enabled the change.
 The Diplomat Murder Case and the Library Murder Case
Heiji Hattori gives Conan a cup of baijiu as a remedy for his cold, causing Conan to change back into Shinichi in the middle of a murder case investigation. He manages to solve the case and escapes before changing back into Conan. Later Conan tries to use the baijiu to change back but finds it no longer works. It may have failed because Conan was no longer afflicted with a cold, but Haibara also considers that that his body built up a resistance to the baijiu after using it once.
Haibara drinks baijiu at Conan's prompting in order to escape the locked alcohol storage room Pisco had trapped her in at the Haido City Hotel. She is able to scale the chimney in her adult form to leave the locked room. Her half-drunken left-behind bottle is noticed by Vodka, but neither he nor Gin realize its purpose. After being confronted by Gin on the roof, she falls back down the chimney and turns back into Haibara. Pisco sees her reversion, but is unable to tell anyone before Gin kills him.
Conan took some of Haibara's medicine to create the symptoms of an awful cold and then drank baijiu. He became Shinichi for around an hour, but felt terrible as a result.
Conan and Haibara accidentally returned to Shinichi and Shiho when they ate some alcohol-containing cake.
- In an interview in Conan Drill, Aoyama claims that the name of the alcohol comes from the name of a villain in Lupin III.