Thirteen-year-old Taro Kagami is a mild-mannered student who struggles with the harsher side of middle school. One day, on his walk back home, he finds a black notebook with the English title "Death Note." As he only understands the meaning of "Note," Taro assumes it's an ordinary notebook and takes it home to use as a diary. To vent his frustrations, he writes in the diary about his day and details how two of his classmates bullied him. Shockingly, the very next day, he is informed that those two students died of heart attacks.

When he learns the meaning of the word "Death," Taro starts to believe that the diary can kill whoever's name is written inside. The appearance of the shinigami Ryuk, the original owner of the Death Note who now stalks Taro, only confirms his theory. Now armed with this deadly weapon, Taro must decide what course of action he will take and whether he is capable of wielding such a disastrous power.

Note: The one-shot was later published as a bonus in the guidebook "Death Note Volume 13: How To Read", then later in the volume "Death Note: Tanpenshuu".