Well, I'm a bit jet-lagged still - but going from memory I seem to remember reading on the Amazon.ca description that they say "Sun is the longest chapter in the Phoenix series, and its structure is threefold. Harima's story in 7th century Japan interweaves with that taking place in the 21st century, while another tale of a spiritual battle bridges both past and future." (ok... that wasn't quite 'just from memory'
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The key words being "longest chapter" and "threefold". Going on those alone I'd guess that we're looking at 3 volumes for "Sun" and 12 volumes in total (unless they also decided to include the "Shonen Club" 3-part series - but somehow I doubt it).
