It is possible to encounter the ghost of a dog. In addition, some enemies can be tamed by the player and acquired as pets, making it so killing them could be considered as killing pets.
Luke is implied to be the same age as the player character, who is often referred to as "kid" and described to be young. Luke dies at the end of the ghost ship, but he is revived in the true ending. The player's own death in gameplay may also be an instance of this.
They are mostly static background elements in one specific area of the game, and smaller spiders can also be obtained as a charm to have them follow around the user at will.
After the end credits, for the normal ending, a mysterious character will show your progress towards the true ending. In the true ending, the world's goddess restores the life of a certain character.
The player's mother dies before the game begins, and this is shown in a cutscene about halfway through the game. In the normal ending, the player's father also dies.
After defeating Dad, he will try to sacrifice himself for the player. In the game's normal ending, he dies. In the game's true ending, he is saved before this happens.
It is possible to fish in certain areas, there is a port town, and a section of the game is on a large ship (although there are very few instances in which it's possible to see water from the ship).