Start by preparing the scrambled eggs. Crack the eggs into a mixing bowl and add the sugar, sake, and salt. Whisk vigorously until the mixture becomes smooth and slightly frothy.

Heat a non-stick skillet over medium heat and add a small drizzle of oil. Pour in the egg mixture and allow it to sit for a few seconds until the edges begin to set. Stir gently, breaking the curds into small, fluffy pieces. Once just cooked through, remove from the pan and set aside in a bowl. Wipe the skillet clean for the next step.

Return the pan to the stove and add the ground chicken, with a touch more oil if needed. Sauté over medium heat until the meat is no longer pink and begins to take on a light golden color.

Add the oyster sauce, soy sauce, sake, mirin, and sugar to the pan. Increase the heat to high and cook the mixture, stirring occasionally, until all the liquid has evaporated and the chicken is well-coated and fragrant. Remove from heat.

Bring a small pot of water to a boil and season with a pinch of salt. Add the Oriental spinach and blanch for about one minute, just until vibrant green and tender. Drain the spinach well and gently squeeze out any excess water.

Transfer the spinach to a small bowl and season with soy sauce, sugar, sesame oil, and toasted sesame seeds. Mix thoroughly until the leaves are evenly coated.

Spoon hot, freshly cooked short-grain rice into two serving bowls. Arrange the scrambled egg, chicken soboro, and seasoned spinach in neat sections over the top of the rice, creating the traditional tricolor appearance.

Finish each bowl with a small amount of red pickled ginger, if desired, for a bright, tangy accent. Serve warm and enjoy immediately.