Infinite Dendrogram Manga Omnibus Volume 3 contains volumes 5-6 and features story by Sakon Kaidou with art by Kami Imai.

You know how it is: Show up, destroy a band of necromancers, defeat the boss, and go home to blow your winnings at the gacha spinner. Too bad Ray never has it so easy, and this time, the boss left behind a trap that turns the local bandits into a gigantic, gruesome, grudge-powered gross-out monster - with his own soul at the center. Can Ray figure out how to take it out on his own? And wait, why's there a flashback?! Watch out for that truck!