(Disclaimer: I know very little about any of the people mentioned. Everything I'm getting comes from this blogpost (archive, archive), this, this (archive) and some time on Japanese Wikipedia.)
A native's name is the first part of the given name of the person being referenced, and the kanji on their forehead is the first character of that person's surname. This can be complicated by the Japanese tendency to use professional names more than the west does, but things eventually line up.
Jun is Oki Junkichi, alias Oohori Junta, who started off as an assistant director on Ultra Q, and worked on many, many more Ultraman shows. He directed the banned episode 12 of Ultraseven.
Jisso is Jissoji Akio, alias Kira Heiji (English), a widely accomplished director who achieved recognition outside of Japan and also worked in opera. Jisso's tendancy to hide his face probably comes from Jissoji's well-known personality. (I originally rendered the name as “Jissou”, but I've fixed that now.)
Ko (who doesn't get named in this chapter) is Kawakita Koichi (English), who worked on a bunch of Godzilla films, and also Gunhed. (I originally thought the the kana might be read as “Kor”, but that was definitely a mistake of mine.)
Toru (who I think hasn't shown up before) is Narita Toru, alias… Narita Toru, but spelled differently (English), who designed Ultraman along with a bunch of other things.
Shuu (who showed up for one panel in chapter 23) is Kaneko Shusuke, who worked on Gamera.
Yo (who has shown up before, but only got named in chapter 23) is Kobayashi Yoshiaki, a special effects director. He has been called “Japan's John Carpenter”.
There are a bunch more, including some who haven't shown up yet.
Oh yeah, and the Strongest Man also does some stuff this chapter as well.