Browsing the on-board library on v2.0, I came across the "Welcome to Kobo!" document in Japanese (Kobo へようこそ).
In the section named "文章を選択する" (tr. "Selecting Text" or "Annotations" in the English document) the reference to using the dictionary is omitted. Could this mean that the JP version will not have this function when released on the 19th?