Prepare the brine by combining water, salt and sugar in a saucepan over high heat. Stir until the sugar and salt dissolves. Remove from heat and set aside to cool.
Add chicken pieces into the cooled brine and refrigerate for 3-4 hours. Take chicken out of the refrigerator and remove from brine 30 minutes before deep frying.
Grind 3 packets of noodles into powder form using a spice grinder (it helps if you break them into smaller pieces before adding into the grinder).
For the last packet of noodle, pound it into small bits by using a mortar and pestle (or by placing it into a zip lock bag and pounding with a rolling pin). This is to get small crunchy bits of noodles into the batter.
Mix both types of ground noodles together. Add 2 packets of seasoning into the mixture and combine well.
Mix 1 packet of seasoning into the buttermilk. Coat chicken pieces with the buttermilk mixture.
Heat oil in a deep fryer (170ºC or 340ºF). Working in batches, remove chicken from buttermilk, dip into ground noodles mixture, and add into oil. Cook until crispy and golden brown to an internal temperature of 75ºC or 165ºF (depending on the cut, it may take between 6 - 12 minutes).
Remove cooked chicken from the fryer and place onto a wire rack. Sprinkle the remaining packet seasoning contents, some shichimi togarashi and yuzu powder over chicken while still warm.
For the slaw, combine shredded red cabbage, cooked edamame, goma dressing, kewpie mayo and shichimi togarashi and mix well.
Serve chicken hot with the slaw.
Recipe adapted from David Chang (http://luckypeach.com/recipes/ramen-fried-chicken/)