There's a mention of a portrait of Sai. Why was there a nine-year delay in the narrator explaining its story?

The delay in explaining the story behind the portrait was due to circumstances and the passage of time. As recounted in Chapter 41, the narrator and a priest named Ismu made a firm determination to place the portrait in what they considered its rightful place. The narrator presented the image but had to leave immediately because he saw that a meal was ready. He intended to share the long story behind it 'later at leisure,' but this opportunity did not arise. A full nine years passed before an unexpected meeting occurred, which finally allowed the narrator to recount the past history associated with the powerful Sai portrait.