In volume seven of Blue Exorcist, the Impure King arc continues. It turns out that Mamushi Hojo is the traitor, and working with Hojo. She seems to be under the impression that they are taking the eyes to a safer place. Todo’s actual plan is to awaken the Impure King, which Mamushi finds out much too late to do anyone any good. The reason why he wants to seems to be to flush out Tatsuma and steal his familiar Kurakara. He does this successfully and runs off. (Some part of Kurakara stays with Tatsuma, which was slightly confusing.) Tatsuma’s familiar is a demon whose contracts depend on deception and secrecy. (This is why Tatsuma has been so avoidant and secretive.)
We learn more about the connection between Fujimoto and Tatsuma Suguro. It seems that Fujimoto was able to cure Tatsuma’s wife and some monks of a serious illness. In return, Tatsuma allowed Fujimoto to steal the Koma sword. We also learn that Fujimoto’s original plan was apparently to use the sword to kill Rin, not bind his powers. The letter ends with a plea that Rin use his flame on the Impure King, which will hopefully destroy it.
Rin wants to help! Unfortunately, he cannot help because he cannot draw the sword. Shura diagnoses this as Rin having lost confidence in his ability to control the flames. (To be fair, he has not actually gained full control of them yet.) This is very much a problem!
What is even more of a problem is that Mephisto turns up with news that Rin has to die. Then he uses some kind of clockwork demon to seal the sell. He tells Yukio and Shura about the Impure King and makes it clear he is not going to be sticking around because of severe Impure King allergies. At the same time, he broadly implies that they should find a way to break Rin out, and gives Shura the sword.
While Yukio joins up with the exorcists getting ready to take on the Impure King, Shura takes the Koma sword to Ryuji. She also gives him the letter Tatsuma wrote to Rin. Ryuji reads the letter and realizes he should break Rin out. This is a somewhat controversial idea among the kids, but Ryuji is pretty determined to have his way. They head down to the pokey where they encounter the clockwork demon Mephisto left behind. No one is able to approach it except Shiemi, whom it does not regard as a threat. (Shiemi is somewhat upset she is not bad ass enough to be seen as a threat. Count your blessings, you silly moe darling.)
On the other side of the door, Rin is feeling extremely sorry for himself. And by sorry for himself I actually mean “extremely depressed.” Shiemi gives Rin a pep talk and reassures him that they’re still friends. Rin and Shiemi are able to leave the cell and everyone apologizes for being standoffish. (Though Izumo claims to only be following Shura’s orders and Renzo claims he didn’t want to come.) Ryuji meanwhile takes the opportunity to yell at Rin because he keeps trying to do things on his own, without his friends. (Give Rin a break Ryuji, Rin is not actually used to having friends.)
Though Rin is still not able to use his flame, everyone goes to the main temple where the Impure King is growing. Yukio is on the scene and the volume ends with a confrontation between Todo and Yukio. The pacing was a little drawn out, but with such a huge cast, it is not that surprising. We get some interesting here and I really loved the interactions between Rin and his friends.