A cold bottle of milk after a bath has become one of the best-known images of Japanese bathing culture.

But it's not an ancient tradition.

The custom became popular after the Second World War, when milk was widely promoted as a nutritious drink. Public bathhouses were ideal places to sell it. People stepped out of a hot bath feeling thirsty, and chilled glass bottles of milk offered a simple, refreshing way to cool down.

People began to expect it. Children grew up doing it. Before long, drinking a bottle of milk after a bath simply became part of the sentō experience.

For many Japanese people, the familiar clink of a glass bottle, the satisfying pop of the foil cap, and a cold drink after a hot soak became part of the sentō experience itself.

Today you'll still find milk in many bathhouses, although sports drinks, tea and fruit juices have become just as common. Even so, the bottle of milk has never really disappeared. For many people, it just doesn't feel quite like a trip to the sentō without one.

Every ritual has a history.

The Yū Journal explores the stories behind Japanese bathing, from everyday customs to centuries-old traditions. Join our mailing list and follow the journey as Yū Bathhouse takes shape.