Shochu refers to the Japanese low-class distilled spirits, made from rice, corn or wheat. It is distilled as compared to Sake which is brewed. Moreover, as compared to Sake (12 - 15\% alcohol volume), Shochu is much stronger, usually about 35 or 40\% alcohol volume. It is the cheapest drink in Japan as measured by its alcohol content, only about the same as price or cost of Sake
Other definition:
Shochu refers to a traditional Japanese distilled beverage. Shochu is Japan's other indigenous alcoholic beverage, but unlike sake, shochu is distilled. It is also made from one of several raw materials. The alcoholic content is usually 25\%, although sometimes it can be as high as 42\% or more.