[scottfab]

Kenji, I certainly agree with others you should check the master and slave cylinder as well as fluid level however, based on what you have described you may have lost the 1 & 2 gear synchro.
Unfortunately if this is true, it is not easy to fix.
I have rebuilt the ZF6 transmission before. It is doable but you must be brave and make sure you have the a 10 or 20 ton press available.
I can point you at a CD that walks you through the process if a rebuild becomes necessary.

I hope the cyclone now in Japan is not where you are.