On talk of the monster arc, it does suffer from a lack of focus on development of the MC and is more subdued in its world building, you would have thought it would have been the setting that would test him but they never seem to be in any serious danger up until the very last part, it did have some great atmosphere though.
But by far its strongest contribution to the narrative was making the main characters feel like people who know each other and would fight together, feel like a team. Before the arc, the MC's original friends, Alice and Michael, Ella, these 3 different groups didn't have much to do with one another. But the MC is long overdue a good fight.