I want to know the answer to the following question:
The Pillow Book was a collection of whose observations of the imperial court?
All the background I'm provided with is that "The lyrics of the modern Japanese national anthem, Kimi ga Yo, were written in the Heian period, as was The Tale of Genji by Murasaki Shikibu, one of the first novels ever written.". Is that enough to answer the question?