Prologue

A huge castle made of stone and steel floating in an endless sky.

That was all this world was.

It took a vagarious group of craftsmen one month to survey the

place; the diameter of the base floor was about 10 kilometers — large

enough to fit the entirety of Setagaya-ku within. Above, there were 100

floors stacking straight upwards; its sheer size was unbelievable. It

was impossible to even guess how much data it consisted of.

Inside, there were a couple of large cities along with countless

small scale towns and villages, forests and plains, and even lakes. Only

one stairway linked each floor to another, and the stairways existed in

dungeons where large numbers of monsters roamed; so discovering

and getting through was no easy matter. However, once someone made

a breakthrough and arrived at a city of the upper floor, the «Teleport

Gates» there and of every cities in the lower floors would be connected

making it possible for anyone to move freely through these levels.

With these conditions, the huge castle had been steadily

conquered for two years. The current front line is the 74th floor.

The name of the castle was «Aincrad», a world of battles with

swords that continued floating and had engulfed approximately six

thousand people. Otherwise known as...

"Please...Don't leave me alone...Pina..."

Two lines of tears streamed down Silica's cheeks, as scattered

grains of light burst from the big feather on the ground.

That pale blue feather was the remains of her sole friend and

partner for a long time, the familiar «Pina». Just a few minutes ago,

Pina died protecting Silica. Given a mortal wound by the monster's

weapon, it gave out a cry in a sad voice before shattering like ice.

Leaving only its long tail feather which had always waved happily

whenever its name was called——

Sword Art Online Volu