In 2017, a group of genius scientists achieve a remarkable breakthrough in bioengineering. However, all the new technologies are put into military use, beginning a new round of arms race. Vanguards, as the most significant achievement of the modern bioengineering and the most advanced weapon, are widely utilized in the race. Although vanguards are exceptionally combat-effective, their life expectancy is shortened by the nanomachines they use. Usually, most vanguards will retire from the army after a number of years in service.