Thanks for playing it!
Yeah it isn't obvious that you've been hit and I also noticed myself that standing in front of the enemies heads prevents you seeing the attack animation as well, which really doesn't help!
It should go from day 3 straight in to the boss battle and the player won't be there as it's just the companion fighting, the idea was that you would try to train him to a point where he can kill the boss on his own but there's currently not a lot of feedback to the player as to what is happening in the game.