“In Summer-the night, moonlit of course!
It's beautiful when fireflies are dancing everywhere in mazy flight.”

The Pillow Book is a famous collection of essays written by Sei Shonagon (966-1017) whilst she was in the service of Empress Teishi.
The Pillow Book was thought to be a way for her to express her innermost thoughts and feelings which she was unable to express publicly due to her lowly position in court.
Sailor Pen has skilfully created the colour of the sky that she described in this essay.