The friends Kaori, Erika and Aki are on a vacation to
celebrate their upcoming graduation, when suddenly an
infestation of mysterious walking fish forces them to
reevaluate everything they care about in order to stay
alive.
Gyo (ギョ?, Fish) is a horror manga by Junji Ito. It also
includes a pair of bonus stories, titled The Enigma of
Amigara Fault and The Sad Tale of the Principal Post. An
anime adaptation by Ufotable was released on February
15, 2012.
The plot of Gyo centers around the "death stench", a
revolting smell first encountered in connection with
creatures appearing to be the corpses of bizarre fish
with scuttling, sharp metal legs. At first they appear
merely as smaller fish, but later also as larger sea
creatures such as sharks and even a whale.
The creatures are eventually revealed to consist of a
small metallic, multi-legged structure with the carcass
of a dead animal (and later, human) strapped on top.
Germs infecting the rotting body produce a gas -
responsible for the terrible smell that surrounds the
creatures - that makes the metal construct move.
Later, it is found that the Japanese Army was
researching germs that produce the death stench during
World War II in a desperate effort to turn the tide of
the war. Infection by the germ produced large amounts of
foul-smelling gas from body tissue, and since infection
quickly killed the test animals, walking machines were
built to carry them farther, allowing them to reach and
sicken enemy troops. Enemy planes sunk the ship carrying
the prototypes for the walking machines, which ran
entirely on the gas.
Underwater the machines have attached themselves to the
fish and moved from the island to the mainland,
attacking the humans. Later it is found that the death
stench gas might have a will of its own, and that the
machines are not man-made: the disease has apparently
mutated to be able to construct the walkers from the
metal hulls of sunken battleships.