Toso (?), or o-toso, is spiced medicinal sake traditionally drunk during New Year celebrations in Japan.
Toso is drunk to flush away the previous year's maladies and to aspire to lead a long life. For generations it has been said that "if one person drinks this his family will not fall ill; if the whole family does no-one in the village will fall ill", and has been a staple part of New Year's osechi cuisine in Japan.
Toso is written using two Japanese characters: representing evil spirits and meaning to defeat.
Toso is made by combining several medicinal herbs to form tososan (屠蘇散?), a spicy mixture, which is then soaked in sake or mirin. If made with mirin, essentially a sweet sake, it is suitable for drinking, but using fermented mirin seasoning would not be appropriate as it is too salty.
Three sizes of cup, called sakazuki (盃?) (see picture), are used starting with the smallest, and passed round with each family member or guest taking a sip. Drinking rituals differ by region, but in formal situations would proceed from youngest to eldest. This tradition originated in China whereby the young effectively test the drink for toxins. However, in Japan, around the beginning of the Meiji or Shōwa periods, custom changed and the head of the household usually takes the first drink.