[file read error]

That can be caused by your character blocking while you save. The game doesn't correctly remember that you're in "blocking" mode, yet it doesn't fully restore you to "standing" mode again, but unfortunately I don't remember how I managed to move again in such a situation. It could be something else in your case, however (maybe you were just casting a long-duration spell like ice shards or solar rays while you saved?).

Do you have an earlier savegame? If yes, you can still rescue Yamamatsu by always casting ice shards on the ninja enemy and then opening the inventory while the spell hits the enemy. If you do this a lot of times the enemy will hopefully drop dead, assuming you don't run out of spells (and even then, you could just let the game run for some hours to recharge the spells).