Sprinkle the salmon with 1 teaspoon of salt on all sides and place it on a few layers of paper towels set on a rack. Refrigerate the salmon overnight.
To make the rice, wash it in a strainer until the water runs mostly clear. Add the rice to a heavy-bottomed pot along with the water, sake, and konbu. Cover this with a lid and let the rice soak for at least 20 minutes.
When the rice is done soaking, turn the heat on to high and bring the mixture to a boil. As soon as it's boiling, turn down the heat to low and set a timer for 12 minutes. Do not open the lid during this time.
When the timer goes off, have the salmon ready to go into the pot with one hand, and use the other hand to open the lid (careful, the lid may be hot). Quickly slide the salmon in over the rice and close the lid immediately.
Set a timer for 15 minutes and let the rice and salmon steam.
When the timer goes off, remove the salmon from the pot. When it's cool enough to handle, remove, and discard the skin and any remaining bones. Add the salmon back into the rice and stir it all together.
Serve Japanese Salmon Rice in rice bowls. You can garnish with ikura and mitsuba if you like.