Nik pointed out to me that on the wikipedia page for Ryuuki, it says:

“It is still unknown whether Shurei will eventually become his consort, but the novels’ narrator says that a painting by Yūkoku Heki (a genius artist from the Heki clan) of Shurei and Ryuki gazing at the sakura trees side by side will be famous for many years to come.”

However, actually when I look at the end of novel 9, I can’t see this information? It’s possibly I’m looking at the wrong place in volume nine, but I don’t even remember reading this. Anyone who read volume nine remember more about this detail?

[EDIT: With the help of Ruby, the mystery is clarified!

What Yuukoku Heki and Banri are actually painting is Ryuuki and Shuurei under the sakura... AT THE END OF VOLUME NINE. In other words, what they are painting is a scene from volume nine. Therefore, since it is a scene that occurs at the end of volume nine, I don't think it has anything to do with what happens later in the novels.]