Responses
It started when he trained the Sergeant's body when he first had to save Muhyeok from rampage. It's in the earlier chapters. Subconsciously, his guiding expertise with the new body had increased. I think it was explained when he was bullied in guide training he had to be careful not to show too much progress overnight. Not sure if sexual relations helped to boost the upgrade process cause that's what his leader is accusing Kang about in this chapter 18.
OHHH THANK YOU!!
why does that matter im kinda slow can someone explain why he moved up to an A-class?