Lin Yan inherited the anorectal clinic passed down from his grandfather and became the third generation "family doctor".
In the eyes of outsiders, this clinic hidden in an old alley on the outskirts of the city specializes in treating all kinds of difficult anorectal diseases and has relied on mysterious ancestral medical skills for hundreds of years. Only Lin Yan knows that the shadowless lamp in the clinic with a lampshade made of deep-sea mother-of-pearl and the anoscope on the operating table full of spiral patterns are all "sealing tools" left behind by his grandfather.
The folds around the human anus are the weakest natural gap between reality and the Cthulhu dimension. Those so-called "strange diseases" are just signs of the "deep-diving tentacles" on the other side of the dimension trying to penetrate the gap.
His scalpel is not used to remove lesions, but to use flesh and blood as ink and pain as a curse to carve a temporary seal around the patient's anus; the "laxative" he prescribes is actually a dimensional adhesive mixed with meteorite powder. When the scaly wooden door in the basement of the clinic began to seep out of seawater, and when he saw green stars that should not exist in the anoscope, Lin Yan finally understood the meaning of "every generation of doctors must become the last seal" in his grandfather's diary - his rectum would be the last gap blocking the abyss.
The angle is novel and the plot is well drawn.