Boyuan, I saw you made test uploads to experimental due to this.
I talked with Sebastien Bacher, and with our Ubuntu hats on we are not very enthusiastic. kyotocabinet is currently not in Ubuntu's "main", so we would need to file a main inclusion request, and the related review would result in a symbols file request (compare opencc and marisa).
So if you decide to do this soon, we'll probably revert the switch in Ubuntu for now.
Wouldn't it be better to wait a bit and see what projects such as perl and python do? Also, considering that tkrzw is mentioned as a successor to kyotocabinet, if we would switch to the latter now, we might need to make yet another switch soon.
-- Rgds, Gunnar