The refined rice wine cheongju (also called yakju) is fortified by adding the distilled spirit soju to produce gwaha-ju.

The name suggests that the rice wine retains its flavor after the hot and humid summer, due to the fortification (addition of soju).

The fortified rice wine was a luxurious prestige drink made in the wealthy households of yangban gentries in the early 15th century, but gradually spread and became popular among commonality.

[2] Many legacy gwaha-ju recipes disappeared due to the harsh periods of Japanese forced occupation (1910–1945) and the Korean War (1950–1953).

The fortified rice wine is consumed after 7 days of secondary fermentation.A recipe for gwaha-ju in the 1809 encyclopaedia Gyuhap chongseo states: [3] 1–2 doe (1.8–3.6 L, 0.40–0.79 imp gal, 0.48–0.95 US gal) of white non-glutinous rice is cooked into beombeok (thick porridge), cooled, and mixed with nuruk powder.

A recipe in the 1827 document Imwon gyeongjeji states that ohyang-soju (five flavour distilled liquor) is made by: "brewing rice wine with cooked glutinous rice and nuruk (fermentation starter); adding powdered herbs such as sandalwood, costus, snowparsley, and clove, as well as whole walnuts and jujubes and soju (distilled liquor) after the primary fermentation; sealing hermetically for the secondary fermentation; opening the wine jar after 7 days and sealing again; and letting age for 29 days.

The family recipe uses pine needles, mung beans, chestnuts, ginseng, dried poria, and bamboo leaves.