The Light in the Eyelids

The Light in the Eyelids (瞼の光 Mabuta no Hikari) is the fourth chapter of the manga series. It was later adapted into an anime episode titled "The Light of the Eyelid."

Synopsis
Ginko investigates the case of a girl with a strong sensitivity to light who is forced to spend her days in darkness.

Plot
When Sui is visited by her cousin Biki, she lets him in on a secret: she knows that Mushi are affecting her eyesight. She tells him they live beyond her second eyelid, which lies behind the normal eyelid and blocks out all light. She tries teaching Biki how to do it, but he can't. Biki then wonders why he can see anything at all in the darkness. Sui replies it's because the River of Light flows beneath them, but to see it, one must close their second eyelid for a long time. When Sui initially saw the light, it had appeared small and faraway, but soon it turned into a flood. She has tried to get close to it, but she's always stopped by a man on the opposite side of the river who warns her not to get any nearer.

When Biki returns to the main house, his mother scolds him for spending too much time in the storehouse. Although Biki takes precautions not to catch whatever illness Sui has, his mother is still worried that it's not enough and he'll eventually catch it. But she realizes it's not Sui's fault and feels sympathetic towards her situation, so she asks Biki to watch over her.

Later that night, Biki awakes only to cower away from the candlelight near his bed. He quickly blows the light out, knowing that he has Sui's illness.

In the morning, Biki's mother comes to check on him and finds her worst fear has been realized. When she brings Sui her breakfast, she tells her that Biki won't be visiting her anymore because of what happened. She doesn't blame her niece, however, and only blames herself for forcing Biki to look after her.

She rushes back to her son when she finds the door to the main house open. Ginko is kneeling beside Biki and reassures her that her son is fine and just resting. With Ginko's help, it is possible that Biki can be treated since the Mushi affecting him had recently hatched. He then mentions hearing a rumor about a young girl living in their storehouse.

Meanwhile, Sui is shown feeling tremendous guilt over her cousin's condition. She suffers alone in the true darkness with her thoughts eating away at her.

Biki wakes up suddenly and reaches out to Sui. Instead, he finds Ginko nearby, who asks him how he feels. The treatment was a success and Biki is no longer sensitive to light. The Manako Yami, Ginko tells him, are Mushi that breed in the darkness. He then explains his connection to Sui and how she had been on the other side of the shore when he closed his second eyelid.

Ginko waits for nightfall to begin Sui's treatment only to find that her condition has worsened. Despite Ginko's warnings, she had gone into the river and, as a result, the true darkness ate her eyes. Still, Ginko has a plan on how to lure the Manako Yami out.

In the light of the moon, which attracts Mushi, Ginko instructs Sui to open her eyes while keeping her second eyelid closed. Slime begins to pour out from her eyes, the Mushi drawn towards the moonlight. The slime shoots forward and surrounds Ginko, who quickly finds what he's looking for. He yells for Sui to close her eyes and the Mushi slowly slink back towards her. What is left in Ginko's hand is a dark, centipede-like creature. He crushes its neck and it dissipates into the air.

Biki watches in shock as Ginko then takes out the glass eye from his left eye socket. He uses a syringe to inject some of the liquid Mushi that had come out of Sui's eyes to give the eyeball life, which he then gives to Sui.

The next morning, Sui is able to leave the storehouse and see the world bathed in sunlight once again. Somewhere else, Ginko is taking a break and having a smoke. He closes his second eyelid and is shown sitting near the shore of the River of Light.

Characters

 * Sui
 * Biki
 * Ginko
 * Biki's mother
 * Ginko

Mushi

 * Manako Yami