The joke here is that The Tale of Genji is considered to be the oldest novel in Japan, and quite possibly the oldest novel in the world depending how we define novel. And it's huge. Like, everybody who's been in school has at the very least heard of it. I guess kinda like The Great Gatsby.

One little detail with this setup is that this novel's author is called Murasaki Shikibu. That exact same character for Yukari. One assumption we can play around with is that this is Yakumo Yukari, full stop. However, some circumstance drove her to end up looking like Merry.

If we position this in such a way that Shikibu became a sukima yōkai later (1000s), then that definitely makes her younger than Mokō and possibly Akyū (700s). Murasaki Shikibu was possibly a Fujiwara.

Wait a minute... Murasaki Shikibu... Murasaki Shiki... Yakumo Yukari × Shiki Eiki? 🤔