Mix ground chicken with mirin, soy sauce, and ginger in a microwave-safe container. Cover loosely with plastic wrap and microwave at 600W for 2 minutes. Stir to break up the meat and let cool.

Crack the egg into a microwave-safe container, add mayonnaise, and mix well. Cover loosely with plastic wrap and microwave at 600W for 1 minute. Stir until crumbly and let cool.

Cut komatsuna into bite-sized pieces using kitchen scissors and place in a microwave-safe container. Add 1 tbsp water, cover loosely with plastic wrap, and microwave at 600W for 1 minute. Drain water, mix with salt, garlic, sesame oil, and sesame seeds, then let cool.