Aftermath and reason

The atmosphere got calm after the sudden boom and the pink flash of light inside this dark fog.

This fog-like darkness was a skill, a powerful one, and I knew aside from Rein, no one could see inside here.

They can't see, and that was for the best.

I didn't want them to see me coughing blood like this, and neither did I believe they would just stand still like that after seeing even a drop of blood on me.

But it can't be helped. 

The headmaster was in his own world, remembering some past events that might have happened while learning from his master.

I didn't know this reaction would be this deep, it was my mistake to not consider this possibility.

But he was more than capable enough to come out of those trains of memories and emotions on his own very easily.

I knew he was deliberately not doing that fully knowing he was safe and nothing would happen to him and that 'I' would take care of the aftermath like this.