Read about it here on Anime News Network.
According to the article he “Hana wa Saku” (Flowers Are Blooming) song’s instrumental recording is complete, and vocals are now being recorded. 33 singers, celebrities, and sports figures who hail from Miyagi, Iwate and Fukushima Prefectures — the prefectures hardest hit by the diasters — are contributing to the vocals. Kanno, as well as Iwai, are from Miyagi Prefecture, and their hometowns were affected by the disaster.
The people in the affected area are still not out of the woods and still need help. Please see the links under the “Assist Japan” section on the right if you are able to help.