On this episode, Yuushi's book revealed itself to Mizuki. Later, Yuushi starts his spiritual training with Akine.
So it's kinda weird to see Mizuki not that surprised when he saw the magical book. Also seeing Yuushi start his his spiritual training was interesting. Other than that, I can't wait to see Mizuki visit the apartment complex and how he'll react towards the spirits. Overall, decent spirit plot for Mizuki and more story development.
Conclusion: Decent spirit plot for Mizuki and more story development.