Chilsung Cider (칠성사이다) is a carbonated beverage marketed by South Korean firm Lotte Chilsung. It was introduced in 1950.
It is not "cider" as the term is usually used in the English speaking world. In South Korea the word "cider" means a sweetened carbonated drink similar to Seven Up or Sprite.
Chilsung Cider is similar to Seven Up but a little sweeter. Other Korean ciders vary in flavour from lemony flavour to more like the smooth sugary flavour of red Fanta or "creme soda."