Master Kinsella will be replaced by the muscular guy as the instructor.
Step-by-step explanation:
The passage uses a well crafted pattern for a lead up to the reveal.
It shows the protagonist to be in a good mood at first and also being able to learn and being completely fine with the life at the class.
They are also shown to be close to the current master as the narrator wants to tell them about the mundane fight and the altercation at school.
This leads up to the reveal that shakes him up for good which is that the teacher will be changed and the normalcy of his life will be challenged.