Mochizuki General Hospital boasts some of the most well-trained nurses in town. But though these ladies spend much of their day battling sickness, their after-hours are spent fighting a very different sort of disease... Under the leadership of the hospital chairman, a handful of staff members and local teenagers form a group of mercenary assassins, targeting the "cancers" of society and excising those individuals before their wickedness spreads.

After an interplanetary war at the beginning of the 21st century, planet Earth has been left in ruins, with much of its ecosystem completely destroyed. Because it was no longer possible to live a normal life on this planet, the inhabitants are forced to move on to other planets where life will, hopefully, be more comfortable.

学校の屋上で漫才の練習をしていたユウとノブ。同じ頃、校舎の中は人間ではない「別のモノ」の存在であふれていた。「別のモノ」に噛まれて死ぬと、同じく「別のモノ」となって人を襲うようになるという。混乱した学校で、ユウとノブ、そして生き残った生徒たちはその魔の手から逃れることができるのだろうか──。