From the Introduction:
Mamoru circled the Oni, keeping his shield up to deflect the savage blows of the demon's large club. This shield wasn't blocking all of the damage, though: he felt himself get shaken with every hit. Worse yet, his strength was slowly leaking away: keeping the heavy shield up took much of his energy. He needed an opening soon...
Then, the demon clutched its club above its head with both hands, ready to land a devastating blow. That was the chance Mamoru had been waiting for! With the demon gearing up for the attack, its right side was open. He rolled to the right and struck the Oni's exposed flank as its club smashed into the crumbling pavement where Mamoru had stood only moments before.
It was not enough. Unexpectedly, the demon followed up with a wide sweep of its club, catching Mamoru's unshielded left side. Mamoru felt his strength leave his body, the dark power of the Miasma flowing over and out of him.
Minutes later, he opened his eyes again. He was back at the base camp, his captain prodding him with the back-end of his lance. "You died there, boy. All of us did. Got too greedy. Get up, we're going to try again to slay that Oni. Let's hope our power is still there when we get back to its lair."
Miasma is a game where you play a samurai, infected by a dark miasma that has held the Imperial Capital in its grip for centuries. In this game, you will wage desperate battles against the monsters that appeared in the wake of the miasma. To stop the monsters from overtaking all of the land, you will become a monster yourself, and commit your body and soul to the fight.