Ayumi is a high school senior from a prestigious university in Japan, and she's counting down the days until she leaves for her adventures overseas. Things take a turn, however, when she's diagnosed with a heart condition that leaves her with only a few months to live. Ayumi is devastated by the news, but she's determined to make the most of her time left. She try to hide her condition to her friends until she have few days left to live. She is a positive girl and good at hiding secret.