In a small bowl, combine sake, mirin, and soy sauce. Stir to combine.
Heat canola oil in a large skillet over medium heat. Season salmon with salt, then place skin side down in hot pan and cook for 3-4 minutes. Carefully flip salmon and cook on additional side for about 1 minute. Transfer to plate.
Wipe out any fat from pan, then pour in sauce. Bring to a boil and cook until reduced significantly, about 4-5 minutes. Add salmon, skin side up, back into pan. Cook for an additional 2-3 minutes, spooning sauce over the fish, until salmon is cooked through and sauce has thickened and becomes syrupy.