Cut the chicken thighs into bite-sized pieces.
First Marinade: Add the water, sugar, and salt to the chicken and massage for 2 minutes until most of the moisture is absorbed. Let it sit for 10 minutes if you have time.
Second Marinade: Add the soy sauce, sake, mayo, salt, ginger, and garlic. Massage the marinade into the chicken and let it sit for 30 minutes.
Coat with Flour: Mix in the cake flour to help seal in the moisture. Then coat each piece of chicken well with cornstarch for a crispy crust.
First Fry: Heat oil to 350°F (175°C). Fry the chicken in batches for 3-4 minutes until golden brown. Drain on a wire rack or paper towels.
Second Fry: Increase the heat to 400°F (200°C). Fry the chicken for an additional minute to achieve that ultra-crispy exterior.
Serve hot with a squeeze of lemon, a side of mayo, and a sprinkle of Shichimi Togarashi for a little spice.