Bitter Kas was born in Vitoria in the 60s and a few years later it had already become the most popular non-alcoholic drink when it comes to aperitifs. Its color and characteristic flavor gradually gained followers and the soft drink became a success in Spain. The traditional presentation of this drink was with ice including an olive and an orange slice.

Its appearance is red with bubbles and its taste is slightly bitter. This drink was already consumed in Central Europe and, above all, in Italy. The company Kas imported this drink and changed the formula to adapt it to the Spanish market. That's why he had the help of Dr. Hausmann, a pharmacist and professor at the University of Barcelona and an expert in medicinal plants.