to english speakers who want to hear spoilers from the 2nd to 4th chapter:
His manga gets roasted by his sensei and he’s told to bottle his feelings for violence lust. The black haired popular girl finds out about his violence lust, she has it too, but she uses it to blackmail him into becoming her sort of slave. There’s no interaction with yachimidori beyond that the she might’ve seen the MC’s violence lust manga and that the MC was apparently laughing when he saw her caught topless by the class.
Vol 6 is not the last because it only includes up to chapter 52. I don't see they cram the remaining 16 chapters into a volume so the series will likely have 8 volumes in total.