Isaki is the name of Minai's monk and Hazama is the centipede guy from the seven stars. I agree with you about Isaki, I didn't care for his character much, but I actually liked Hazama. I don't remember who the old guy was. My least favorite character is Flesh; she received little character development compared to characters like Minai or Itsuki, and her otaku-ness can be overbearing. I think Keisei already brought an element of otaku-ness into the show so Flesh's character seems to be forced into bringing back these jokes.