And if you want more info on Ramune, the all-knowing Wikipedia has you covered:
"Ramune is widely known for the distinctive design of its bottle, often called Codd-neck bottles after the inventor, Hiram Codd. They are made of glass and sealed with a marble; the codd head is held in place by the pressure of the carbonation in the drink. To open the bottle, a device to push the marble inward is provided with the bottle. The marble is pushed inside the neck of the bottle where it rattles around while drinking.
People trying Ramune for the first time sometimes find it difficult to drink, as it takes practice to learn to stop the marble from blocking the flow. In the new version of the bottle (2006), little slots were added to the cap where the marble was originally held. This prevented the flow from obstruction if the marble falls back into the cap.Ramune is one of the modern symbols of summer in Japan and is widely consumed during warm festival days and nights.
The bottle's design creates a special attraction to children who clamor to see the "alien head" image that is formed from the ball and indentations on the bottle neck. This provides a unique form of endearing brand recognition, even for children who don't remember the product's name."