Mika(Aragaki Yui) is a girl who has never fallen in love before, but when she loses her handphone before and gets it back, her summer holidays were occupied with phone calls and mails from a stranger. It turns out that the stranger was a schoolmate of hers, Hiro(Miura Haruma). They soon fall in love and before long engage in sexual activity. Just as their relationship was going on well, Mika was kidnapped and raped by a group of guys instructed by Hiro’s ex-girlfriend, Saki, as a form of revenge. Hiro gets all furious and goes out to get revenge, but the matter was no longer further pursued when Mika was pregnancy test was negative.

But after a while,They soon result in Mika getting pregnant, but she loses it after a fall caused by Saki’s push. Devastated, she and Hiro both “built” a grave for their unborn child and promise to go back to it annually on 24th December, the date of the loss of their child.

Soon after that incident, Hiro started avoiding Mika, and they eventually break up. Mika gets another boyfriend, but is still in deeply in love with Hiro. When she discovers that Hiro was avoiding her because he was diagnosed with cancer, she leaves her poor boyfriend to be with Hiro in his last days. Hiro dies, and Mika has to to continue living on strongly in this world.