This syrup is essentially OPEN BOOK’s secret sauce—now bottled and commercialized to be virtually identical to what we serve at our shop. Mix it with shochu for an exceptional lemon sour, or with soda water for a refreshing, non-alcoholic lemon squash.

People often ask what kind of alcohol it pairs well with. At our bar, we use kokutou (brown sugar) shochu. But at home, you can absolutely use whatever is convenient—like ko-rui (neutral) shochu or even gin from your local convenience store. It surprisingly works with sweet potato shochu, too. Part of the fun is discovering your own favorite mix.
And here’s a little secret: if you use barrel-aged spirits, the flavor becomes exceptionally rich. It’s a level of luxury you won’t find in a bar—so treat yourself at home.

In winter, mix it with hot water for a warming lemonade.
Or add it to beer for a light and refreshing Panaché beer cocktail.

At OPEN BOOK, we typically use 20–30% alcohol in the mix. With a general ratio of 1 part alcohol to 3 parts soda, the full formula (syrup : alcohol : soda) ends up as a slightly confusing 1:3:9. We apologize—but we trust in your mathematical abilities.

This 500ml bottle has a generous 1-year shelf life, so you can enjoy a long-life lemon sour lifestyle.
Makes approximately 15–16 servings of lemon squash.

Orders typically ship within 2–3 business days.
(Delivery may take slightly longer for remote islands.)