A Sea of Writings is the twentieth episode of the Mushishi anime series.
Ginko comes to a house which has a library full of mushi-related scrolls. There, he meets the girl who writes the scrolls, and hears the story of the curse that has been afflicting her family for generations.
There lives a girl whose leg is paralyzed because of a mortally dangerous Mushi which resides inside her. The girl is a descendant of a woman who agreed to contain this Mushi to help overcome it by imprisoning it in a human body, but it was not defeated, it continues to live in the bodies of her descendants. That Mushi was a horrible creature aiming to kill all living things, Mushi, beasts, and humans alike; it appeared long time ago during a natural disaster, a vast drought, that endangered all. No record of its appearance or properties survived, no one knows what it was like and what it did, how and why did it want to kill everything and everyone.
The girl's name is Tanyuu Karibusa; she lives in a lone house away in the wilderness along with an old Mushi-shi, Tama, who had brought her up and had thought her a way to quell that Mushi out of her body with time. She writes down all the tales about Mushi which she has been told by her teacher and other Mushi-shi guys, who mostly told her about killing it. The Mushi comes out of her and is sealed up in the scripts she makes. She's grown sick of those cruel tales, and at that time Ginko comes to meet her and tells her stories of another kind.
He visits her again and goes to read the archives, while Tanyu is resting. When Tanyu wakes, Tama goes to inform Ginko, but he sees bookworm eating the scrolls and warns Tama. Characters from the scrolls then escape them and head out of the basement, but get stopped in the outside room where Tanyu is. He explains the walls have a specific paste applied that keeps them and that the bookworms Mushi is her pets. As paper is eventually to degrade, she uses the bookworms weaken the seals earlier and replace the scrolls before the Mushi is able to escape by themselves. She reseals all the Mushi, recalling each of the character from what volume and chapter is. Later Ginko tells her more stories and she writes them down. She requests he take her out for a walk. Outside, she hopes she one day to have fully sealed the Mushi and be able to walk, although she may be an old lady by then, but also fears it she may not be able to do it in her life time and her descendants will also inherit the birthmark. Ginko asks her what she wants to do when she is able to walk and she says she wants to go with him and meet the Mushi he was telling her about it. Ginko agrees as long as he is well and still alive as he can be eaten by a Mushi any day.