From Viz:
In the future, Utopia has finally been achieved thanks to medical nanotechnology and a powerful ethic of social welfare and mutual consideration. This perfect world isn't that perfect though, and three young girls stand up to totalitarian kindness and super-medicine by attempting suicide via starvation. It doesn't work, but one of the girls, Tuan Kirie, grows up to be a member of the World Health Organization. As a crisis threatens the harmony of the new world, Tuan rediscovers another member of her suicide pact, and together they must help save the planet from itself.

Note: Won Seiun Award and Nihon SF Taisho Award in 2009.