Welcome, Mr. Mushroom (キノコちゃん、いらっしゃ～い！, Kinoko-chan, irassha~i!) is the 30th chapter of Dorohedoro.
Straight where the previous chapter left we see Nikaido helpless in the floor looking at the creature that suddenly appeared from her back, Vaux, 13 and Jonson look scared while Kasukabe seems to be quite exited.
In The Magic User World En finally sees Nikaido trough the mushroom man he created, Chota is concern and ask him is he is ok, to his horror En's face was transformed into a bunch of mushrooms and his consciousness passed to the creature in Hole.
In the Hungry Bug the creature is about to kill Kasukabe but Jonson saves him in the last moment as the giant mushroom reveals his face, possessing the same features (and even mask) as En, but with a zombie look (no pupils and a black liquid pouring from its mouth). Vaux tries to attack it with a baseball bat but its subdued and the creature expels more black liquid, dissolving Vaux's body into a mushroom, Nikaido tries to save him but 13 grabs her knowing she could do nothing with the injury in her back. Kasukabe commands Jonson to kill the creature, both monsters seems to be equally strong but the giant cockroach chops one of the mushroom man's arms with his fangs, staves one of its eyes and kicks it to the ground, the creature turn one of Jonson's foot into a mushroom. The professor saves the mushroom that once was Vaux and tells everyone to retreat, Nikaido is weakened because the mushroom man drained all her energy when he grown from her back so everyone locks in her room, as the creature slowly walks upstairs.
Nikaido knows that they are dead if she doesn't do something, and after 13 treat her wounds, she goes to the attic for her old mask, made by Asu if something happens to her, even against her wishes to use it, she jumps and attacks the creature the moment it breaks into the room, destroying it completely, but as the creature dissolves a Magic Door appear and teleport everyone to the sorcerers world, more precisely, in front of En, who welcomes Nikaido.