There was a fire. Kousei lost his mother, his father and his precious little sister, Sanae. One month later he woke up to find himself in a hospital and was moved to pediatrics where he could share a room with other boys his age.

Professor Kimishiro is loved and respected by his students, but disliked by faculty and administration. He's pushed from his classroom by university politics and takes a team to the jungles of the Amazon in search of new medicines and perhaps a chance to gain back his reputation amongst those with influence back home. Instead of cures, his team stumbles upon a lost temple in the jungle, a place the village guides claim to be 'The House of the God of the Black Death'. What are the temple's secrets, and can any man, let alone a mere boy, survive the plague of an angry God?

A level seven earthquake hit the the Kanto area at 4:55am. 10 survivors are stuck underground on the subway; 2 salary-men, a couple with a young son, an old couple, a calm and collective girl, the subway engineer, and their appointed leader, a man who's never worked to overcome the obstacles in life. How will they escape? What can they do to escape?

"It's amazing what people will do to stay alive."

The month is February, but it hasn’t snowed all winter. Kanon’s father is often away on business trips and might be getting a little too friendly with his pretty young female subordinate; which Kanon doesn’t approve of so soon after her mother’s death. Her little brother collects insects, but they’re dying off.
It turns out that these deaths are the first of many a plague to come down. First it’s the insects, inexplicably dropping dead everywhere. Then it’s the rats, looking for a new food source. And things just keep getting worse…
(Source: M-U)

The basic idea is that man is having a hard time finding food and getting rid of their trash, so science comes up with a bio-engineered animal that survives by eating trash, and is then killed to feed humanity. You can guess what may happen if a self-replicating, endlessly hungry killing machine got loose in Tokyo.