An ironic commonality between two rival drinks.
In Japan, beer and sake have a bit of a contentious relationship. Since ancient times sake has been THE alcoholic drink in Japan. However, around the middle of the 20th century, other beverages from abroad gradually infiltrated the market and began unseating the reigning king of booze.
Among them, the biggest threat was beer, with its exotic appeal and appearances in western media that was also being increasingly consumed here at the time. Younger Japanese people found themselves attracted to this new alternative and began shunning the stodgy image of drinking