Poke the skin side of the chicken thigh with a fork several times, then flip it over and make 4 shallow vertical cuts. Spread 1/2 tsp raw shichimi over the chicken.

Roll the chicken tightly from one end and secure the end with toothpicks.

Mix the char siu sauce ingredients (sake, soy sauce, sugar) in a microwave-safe container. Place the rolled chicken inside, cover loosely with plastic wrap, and microwave at 600W for 8 minutes.

Let the chicken rest until it cools slightly, allowing the flavors to soak in.