After reaching Level 100, the Headmaster starts a conversation with you.
The Headmaster tells you to go quickly to the School and meet your teacher, because there is a Special Training Emergency Roundup. You heard that a different teacher will be in charge this time...you wonder what is going on with the Resistance. Go quickly to the Underground Base.
The Job Instructor is not at the Underground Base... Claudine meets you instead. Her expression confirms your suspicion...something must be wrong.