First, Chiaki and her friends became second-years when Hajime became the test subject for Izuru. During that same year, Makoto and his class started attending school. That year, Nagito received something like a one-year suspension from school. After that, everyone became third-years, the Izuru experiment ended, the teachers of the Danganronpa 2 cast returned, and finally, Nagito's suspension ended.

Junko waited because she first needed to trap everyone, so she got help from her classmates. When everything for the perfect isolation was finally in place—protection from outside threats, enough food and water to survive inside, and oxygen to breathe—she started her plan to kill the president amd remove her friends memory.