Spoilers ahead for earlier volumes.
These two are more tightly bound that the earlier works, and this in spite of having episodes by issue they collect. It revolves about Agott's test.
And it turns out, not only is another apprentice, Euini, from another master, taking it, Qifrey signed up Richeh. She resists, but he persuades her.
The three of them have the challenge explained, and set out. Qifrey, and the other apprentice, Tetia, explain history to Coco. There are unexpected issues in the test, and the Brimmed Hats attack, producing trouble.
Volume 5 continues with Qifrey having to protect Coco and Tetia when they've been trapped in the spells cast by now-forbidden magic. Agott tries to help Euini from the Brimmed Hats' magic, and Richeh goes to make sure their task is completed and bring back news. Inventions, discoveries, and offers that will complicate their lives going onward.