Hmm... I might do something to cause this happened, but I am not sure. There has been an input method for Japanese in the SCIM of my Ubuntu till yesterday. I found it just disappeared. Even checking the setup of SCIM, I still cannot found the Japanese input method.
I tried to search some relevant items on the internet, and occasionally saw the term ``scim-anthy''. Oh, yes, I recalled that Anthy is the name of the disappeared input method. What needed to do is just install the scim-anthy again:
$ sudo apt-get install scim-anthy
And during the installation, there was no message showed that the scim-anthy has been in my system. So it's possible that I did something to let the scim-anthy disappear? I am just not sure. :-p