Kaoru Isawa (いさわ かおる) is a worker under Ōtsuki in Squad E in the underground labor camps.
Tobaku Hakairoku Kaiji
He along with Numakawa help Ōtsuki at managing Squad E. He also plays a vital part in Ōtsukis Underground Chinchiro for it to work properly.
Ichinichi Gaishutsuroku Hanchou
He plays a supporting role in the spinoff along with Numakawa.