I kind of wish he hadn't run into his classmates and the teacher. It was more interesting to see him roam around and pick up new people and fight tough enemies.
So no one asked why in 4.3 he meets his teacher and then the next chapter is missing and the one after starts with the story telling from Sheila's side.
Only interesting part of Doi's storyline is whatever his handler is up to. I don't find him interesting at all. MC's story is more interesting because he's actually doing something to try and solve the bigger problem, not just screwing girls all day and getting revenge.