In a pot, heat oil. Add grated ginger and stir until fragrant, a few seconds.
Add ground chicken and stir, breaking up the meat into small pieces.
Mix 300mL water with dashi powder, soy sauce, mirin, and sugar. When chicken is mostly cooked, add seasoning mixture.
Add frozen kabocha chunks to pot. Bring pot to a gentle simmer and cook for 10 minutes or until you can easily pierce through kabocha with a fork.
While kabocha is cooking, make a slurry by mixing katakuriko (or cornstarch) with remaining tbsp of water.
When kabocha is done, remove the kabocha pieces from the pot and into your serving bowl. Add slurry and stir, cooking to thicken the seasoning sauce to your tastes. When sauce is thickened to your liking, pour over your kabocha pieces. (Note: I am often lazy and instead of removing the kabocha, I just stir the slurry right into the cooking pot and serve from there)
Serve immediately as a main or side dish with rice.