I've translated Ryuuji's entry on the situation:
29th December 2010
Zoro
C.C.Lemon Hall oneman live "Hallelujah" - thank you so much.
It's thanks to our company's president, and also all the staff, and all the people who gave us their cooperation, and above all, it is thanks to the fans who supported Zoro, that we were able to perform on that stage - it was one of Zoro's goals, and it was also my dream to be able to do so ever since I started participating in bands
From the bottom of my heart, I'm really grateful for this
Among all this, regarding the announcement of the "hiatus", made on 27th December at 22:00 on our official site
It was a very sudden announcement, and I am really sorry that it made everyone uneasy, upset and worried.
With regard to the details of the hiatus, Taizo (guitar) and Yuuya (drums) have left the band as of 29th December, and with "Hallelujah", we concluded our activities together as Ryuuji, Taizo, Tatsuhi, and Yuuya
We discussed this over and over again, up until the day before our announcement, before we came to this conclusion.
I'm really sorry that it had to be such a sudden announcement.
From now onwards, Zoro will no longer be the four of us, but I will continue to do my very best.
source:
Ryuuji's blog