Place the chicken breasts in the slow cooker.

In a small bowl, whisk together the soy sauce, brown sugar, mirin, and cooking sake (or broth).

Pour the sauce over the chicken.

Cover and cook on high for 3 hours or low for 6 hours.

When it’s done, transfer the chicken to a cutting board and shred with two forks.

Pour the teriyaki sauce from the slow cooker through a fine mesh sieve into a saucepan.

Place the saucepan on the stove over medium high heat and bring to a simmer.

Mix the cornstarch and the water until smooth. Pour it into the saucepan and bring to a boil.

Whisk and cook for 1-2 minutes, until it’s thickened.

Put the chicken back into the slow cooker and pour over the sauce. Toss to coat.

Serve over rice or on a bun. Garnish with sesame seeds and green onions.