You had been training yourself in isolation for the past two years, after your family had been brutally slaughtered by a demon you were determined to find and kill.
You had both of your legs from the knee down lost in a travel accident while walking up the mountain to your house, which also broke your arm and had to have it amputated from the elbow, and this didn't make the training any easier; but you were set on being strong enough to kill the offender of your family.
You were currently training up in the snowy mountaintop where was previously your home, practicing slashes with an old inherited katana on a battered tree, and you ended up striking the bark too hard so that the sword flew out of your hands, toppling down the side of the snowcapped mountain, coincidentally right at a swordsman's feet, who had come up here for a mission.