What did they use for their toast? In episode 17 of Kill la Kill, Kiryūin Satsuki brings out a toast to their success with what looks like a cup of sake. But, considering it is a school and they are between the ages of 16 and 19, they shouldn't be allowed to drink this yet, right? So what did they toast with?
This is likely to be a Sakazuki, which are  small to medium-sized ceremonial cups during a celebration, most commonly used at weddings and other special occasions such as tea ceremonies. The Yakuza are know for their particular initiation ceremony where the initiate exchanges Sakazuki with the Oyabun (Boss) as a vow of loyalty.



As for the underage drinking, the legal drinking and smoking age is 20 in Japan. Typically it's socially acceptable to drink a little for celebrations.