Congratulations! You have been randomly selected by the government... to die in 24 hours!
In order to stifle apathy and to kick start motivation, the government has been utilizing the practice of killing their own people. Not en mass, mind you, but one a day should be enough to keep citizens in line. A "small" sacrifice for the betterment of the whole - This is similar to the idea behind The Lottery, Battle Royale, and Hunger Games, but without inherent brutality of those processes.
The National Welfare Immunization is provided to each citizen as they enter elementary school. The immunization protects against infectious diseases, but 0.01% of the syringes contain a nano-capsule that will kill them when they are between the ages of 18 to 24.
Ikigami is certainly a dark story, but there is a lot of optimism hidden in these pages. Writer/author Motoro Mase highlights as many positive sides of human nature as he does negative. For some of the characters who receive an ikigami, a quest begins. What would you do if today was the last day of your life?