From the English version's publisher, One Peace Books:

A battle ensues over life and death, belief and science, ethics and progress.

Two boys, Sei and Oishi, fall madly in love with Yuko. Her death wreaks havoc on their young lives, bitter memories cease to fade, and their tender hearts cling to the dream of a world where debilitating illness disappears in the face of science. But what would happen if they discovered that all they believed was a lie? Is there still a chance that their suffering may end? Will mercy and love prevail?

This exhilarating masterpiece of graphic fiction begs readers to forget what they know about manga. Within this volume lies a new frontier in storytelling.

Sample in English available at:
http://www.onepeacebooks.com/sample/Breathe_Deeply_sample.pdf