Successfully complete the game, and save when prompted. You can start a new session with your cleared saved game file with most of your previously obtained items and skills. There will be an option to select any chapter to replay with bonus objectives at the cellphone menu. You can now select "A New Day" chapter and go to Shiba-Q Headquarters. At the third floor, you can purchase the Ultimate difficulty as a quest item. The "Another Day" chapter will appear at the chapter selection menu.
