The Corpse Doctor (chapter) is the 12th overall chapter of Tegami Bachi Manga
Dr. Thunderland Jr. is spotted walking down the street catching a bird under a park bench that a couple was sitting upon. Meanwhile, Lag is greeted by Connor and Zazie, to which, the two of them notice that Lag is "overtired." The two of them suggest a medical exam by Dr. Thunderland, which should be routine anyway.
As they walk into the Bee Hive, Dr. Thunderland whisks Steak away into the air and into a bird cage. He threatens to dissect Steak after giving a short history lesson on his research of the creature. Niche goes after him, for he is taking her food away from her. Lag and the others follow her.
Dr. Thunderland is able to escape into his medical office with Steak; however, Niche slices the door to pieces—to which, astonishes Dr. Thunderland, because apparently the door is as solid as gaichuu husks, or like stone. He then recognizes Niche as the child of Maka, and then wants to dissect her as well.
Gauche apparently heard rumors about a man in Honey Waters (place) that calls himself The One Unable to Become Spirit. Dr. Thunderland then commissions Lag to deliver all the "letters" he writes to this man. This begins the trail for Lag to finding Gauche Suede.