How come Koro sensei had tomato juice inside jail? In Assassination Classroom Season 2, episode 8, Tadaomi was fighting with Reaper, and then there was one incident where he faked his death from blood loss with the help of Koro-sensei. And then later it is shown that Koro-sensei was drinking tomato juice, and with the help of his one tentacles he faked that scene and helped Tadaomi.

So my question is: how did he get that tomato juice? Is it possible that he was keeping it from the start, or did he try to escape and then got one?
Explained in the manga:



He bought it beforehand.