Add the chicken breast to your slow cooker and season both sides with salt and black pepper.
In a medium bowl, whisk together the soy sauce, brown sugar, rice wine vinegar, sesame oil, cornstarch, water, nori powder, crushed red pepper, ground ginger, and black pepper until smooth.
Pour about 1/4 cup of the mixture into the slow cooker and spread it to coat the bottom. Place the chicken on top and pour the rest of the sauce on top.
Slow cook the chicken for 3 hours on high or 6 hours on low until the chicken is tender and falling apart.
When the chicken is done, shred the chicken with two forks. Serve the chicken teriyaki immediately served on top of a bed of rice or corn tortillas. Drizzle with the pineapple crema (recipe below), sprinkle with fresh cilantro, and enjoy!