Yuka Kikuchi is one of Rin Yamazaki's friends, and the first to suffer from the curse.
Yuka's appearance consists of shoulder length blue hair with messy bangs. She wears a long lavender dress with brown shoes. Yuka appears to have dark blue eyes.
After being taken hostage by the mermaids, Yuka's whole body and tongue was swollen, her skin dried where it showed a few cracks. Her eyes seemed to have turned into a light brown.
Yuka shows to be very calm through the beginning of the game. She has shown to be very feminine for offering Rin to do her make up. She seems to be the opposite of Rin who shows a tomboyish personality but is her closest friend. According to Yuuta, he describes Yuka as docile and pretty, though he was possessed at the time.
From the first scene, she was seen riding with them and eventually following where all of them were. She talks little throughout the game and because of that, she isn't noticed well until she became 'sick'.
1st Night: She was seen in Rin's view when she went inside her room and saw a dark shadow figure beside Yuka. When Rin wakes up and checks in Yuka's room, she is now seen with boils all over her body and her eyes and mouth wide open. After awhile, if you put in the firewood next to Yuka's bed, she will be later seen dead which will also allow Yuuta to die too by killing himself.
If you light the fireplace, visiting Yuka's bed (out of story progression) will result in the message that Yuka looks calm. If you do not light the fireplace, Yuka will continue to point out that she is feeling cold.
2nd Day: Yuka is seen in Rin's dream when she fell from the shelves and 'Yuka' told Rin about the truth about the mansion. 'You see, I'm a hostage'. The next time Rin visits Yuka in her room (if you didn't light the fireplace situation), Yuuta is seen sitting beside Yuka's bed. Yuuta will then tell Rin how beautiful and docile Yuka is compared to Rin, he then chases Rin outside.
'Yuka' will make another appearance as Rin leaves the house to search for a way to get out off the mountains. Depending on whether Yuka is dead or not at this point of the game, Rin will deny that the apparition is truly Yuka by either stating that Yuka is dead, or that she is back at the mansion. 'Yuka' will then proceed with demanding Rin to take 'her' home.
Yaobikuni: Having lit the fireplace, Yuka dies as her body cannot take the swelling she's succumbed to as the heat in the room speeds up the process. Literally: she bursts as her skin and inner organs cannot keep up with the swelling.
Forever deep: Same as Yaobikuni.
Secrets: She was never healed at the end and was never shown what happened after Seitaro died. It is indicated that she will remain in the house forever, however.
Underwater Dream: She was carried towards the car but it was never shown how she was carried. When they already drove out the creepy mountains and village, Yuka's blanket fell and it showed her, alive and appearing to be well, and asking what happened. Rin, as Yuka's best friend, was so glad she was healed and eagerly embraced her. After being examined at a nearby hospital, doctors conclude that there was nothing wrong with her.