That's a fact, jack!

All but the character in the upper left corner of the illustration has been identified.
I have written a list for those who want to know more details.

Jakotsu→Asai Narumi (Orikasa Ai)
Higurashi Kagome→Oooka Momiji (Yukino Satsuki)
Sango→Akiba Reiko (Kuwashima Houko)
Inuyasha→Kudou Shin'ichi & Kuroba Kaito (Yamaguchi Kappei)
Miroku→Akagi Hideo (Tsujitani Kouji)
Myouga→Agasa Hiroshi (Ogata Kenichi)
Kikyou→Sera Masumi (Hidaka Noriko)
Naraku→Haneda Shuukichi (Morikawa Toshiyuki)