For coloring this page, I suggest using warm and bright colors. The red kimono of the girl can be a vibrant red. The white flowers on the kimono can be painted with a white or light brown color. The black hair of both children can be solid black or it can be shaded with different tones of black, creating a subtle texture on their hair. For the blue kimono of the boy and the white flowers on it, I suggest a light and bright blue for the kimono, and white for the flowers. Furthermore, to make this scene more lively, you can add some additional details with colored pencils, such as streaks of color to the traditional kimonos, or small highlights on the children's black hair.