Add a bit of oil to frying pan, and brown chicken (skin-side down) until the skin is a deep golden color.
In a medium-sized bowl, mix shoyu, brown sugar, water, and rice vinegar.
Transfer chicken to a slow cooker, and our the liquid mixture over the chicken in the sauce pan.
Add in the smashed garlic, sliced ginger, and white parts of green onion..
Set slow cooker on low, and cook for 6-8 hours.
Serve the chicken over a big bowl of white rice. Garnish with green parts of green onions and top with sesame seeds.