Saejima's chapter opens in Okinawa Prison. After a series of dramatic events, including a prison riot, you'll find yourself attempting to escape the facility. This segment acts as a tutorial for Saejima's unique combat style. You'll face numerous prison guards and fellow inmates. Remember to use his powerful charged attacks and environmental objects (like benches and tables) as weapons.
The escape route is fairly linear, but you'll encounter several locked doors and obstacles that require specific actions to overcome. Look for glowing interactable objects. You'll also have a brief stealth section where you need to avoid guard patrols. Pay attention to their cones of vision on the mini-map. Successfully navigating the prison and reaching the outside will conclude this intense introductory chapter, setting the stage for his journey back to Kamurocho.