Chuhai (酎ハイ) is a Japanese cocktail which includes Shouchu liquor and carbonated water flavored with fruit syrup, juice or other sweeteners.  Chuhai has been a popular drink in Japan at bars and restaurants, as well as canned versions you can easily find at stores there.

Shouchu is a clear distilled liquor favored by many alcohol lovers in Japan. Shouchu can be made from various things, such as by distilling rice, potato, wheat, etc. There are generally two kinds of Shouchu; one has a stronger flavor from such ingredients (Otsu kind) and the other with much less flavor (Kou kind), similar to vodka.  For making Chuhai, since the drink is mixed with something else for flavor, the latter more mild Kou Shouchu is often preferred.