What exactly are they alluding to in the bottom panel, here?
The Fujiwara clan held a lot of power during the Heian period which is when the poet (and aristocrat) Yoshika is based on lived. Mokou was likely born a bit before the Heian and has lived since then so she may have heard of the person
Miyako... I feel like I've heard that name somewhere...
Because no one can live as straight and narrow as a bamboo.
Bamboo Forest of the Lost
Although... a daughter of the Fujiwara? No, couldn't be...