Ushio Kofune (小舟潮, Kofune Ushio) is a 17-year-old girl living in Hitogashima. She lost her life in a maritime accident while trying to save Shiori from drowning in the sea. She loves her childhood friend Shinpei, but has yet to express her feelings for him.
Ushio is a young woman with fair skin and a curvy athletic build. She has long blond hair that reaches down to her waist and blue eyes. Her eyebrows and eyelashes are noticeably blonde as well.
One of Ushio's signature outfits is a dark navy blue one-piece swimsuit with white shoulder straps. Ushio also wears an oyster shell pendant around her neck.
On July 17th, while Ushio and Mio shop at Kobe Mart, Shiori shares that she was followed by a look-alike. Ushio believes this was just a creep and tells her to report it to Tetsu Totsumura, however Shiori is disappointed that they don't take her seriously and states that he won't be able to do anything.
On 18th, Ushio helps with cleaning the beach. She sees a flash and as she turns, she sees her shadow. She tries to follow her, but loses her. She goes to Shiori and tells her that she believes her.
At home, Mio thinks that Shinpei will come this year, but Ushio states she doesn't care and can stay in Tokyo forever, however, Mio then teases her that she doesn't mean it as she loves him. Ushio then heads to take a bath, but finds Shadow Ushio in it. Ushio tries to call Mio, but Shadow Ushio stops her. She explains that she is Ushio Kofune and came back to her house, but hid as she saw Ushio with Mio. The two of them then think the other is the Shadow, but then realizes that if Shadows are real, then Shiori's Shadow is somewhere on the island. They recall that Shiori mentioned she saw her Shadow for the first time on Mount Takanosu and agree to investigate it.
The two head in the mountain, but are unable to find anything. Shadow Ushio then sees a sign, stating its dangerous ahead and they decide to proceed. They reach the old Hishigata family clinic, which had rumours to be haunted, making everyone avoids it. Shadow Ushio has a weird feeling of being there before. They hear some noise and see a Shadow holding a crow. The Shadow then flashes and copies Ushio. The third Ushio attacks them and pins Shadow Ushio to a tree. Ushio attempts to attack the third Ushio, but her attacks has no effect. She ends up hitting her shadow by accident, which hurts the third Ushio, who then kicks Ushio away. Third Ushio then stabs Shadow's Ushio shadow, injuring her leg. At first Shadow Ushio is surprised, but then figures that a Shadow's weakness is their flat shadow, which would mean she isn't a human. Shadow Ushio then uses her hair to cut third Ushio's arm and free herself. As third Ushio runs, Shadow Ushio follows her realizing that her real body is the shadow and the projected body is a weapon to protect the real body. She catches up to third Ushio and slashes her shadow, killing her. Ushio tells Shadow Ushio that she is cool. Shadow Ushio then flashes and updates her data, copying her data on her healthy foot and heals her own foot. Shadow Ushio explains that she will eventually disappear, but if she kills the original, she will become the original. Her instincts tell her to kill Ushio, and normally she would have done it by now. Ushio realizes why its said that you will die if you see your Shadow and that Shiori is in danger.
On 21st, at the beach, Shadow Ushio copies Ushio in her swimsuit. Ushio asks Shadow Ushio if she can become her shell necklace and Shadow Ushio turns into it. Ushio then puts on the necklace and takes the real one to her bag. While distracted by Akari, Shiori ended in the water and is drowning. Shadow Ushio tells Ushio that she senses a Shadow under the water. Mio leaves Akari to Tokiko and wants to go and help her with Sou, but Ushio stops them and asks them to leave it to her. Ushio jumps in the water and swims to Shiori, who is being dragged deeper underwater by Shadow Shiori. Shadow Ushio turns back to her Ushio form and slashes Shadow Shiori's arm. She grabs Shiori and heads to the surface, but Shadow Shiori's arm is still on her and surrounds them with shadow arms, immobilizing them. Ushio pulls Shadow Shiori out of them, but Shadow Shiori starts strangling her. Ushio tells Shadow Ushio to ignore her and continue to save Shiori. Moments later, Shadow Shiori catches up to Shadow Ushio, wanting them to stop and Shadow Ushio sees Ushio's body falling down towards the bottom. Shadow Ushio slashes Shadow Shiori, but Shiori manages to grab her and realizes that Shadow Ushio is faulty. She attempts to fix her, but as she senses that Mio and Sou are coming, she releases Shadow Ushio who starts falling towards the bottom, erases Shiori and then acts unconscious for Mio and Sou to save her.
Shinpei finds Ushio at the beach. He tells her she died, but Ushio has no memories and only remembers some pain, and believes he is human. Ushio reveals she wanted to tell him something if he ever came back and then tells him she loves him. He asks her what she wants. Looking at the fireworks, Ushio wonders if its 24th already and as Shinpei confirms, she states she wanted to go to the festival with him. As she goes to the festival, he goes after her and tells her to stay hidden until the festival is over as everyone believe she is dead and can't meet her friends. Annoyed, she punches him, warning him that she will punch him if he keeps saying nonsense. Mio calls Shinpei and seeing its Mio, Ushio takes the phone and greets her, but Shinpei tells Mio its him.
Shinpei goes to his friends at the shrine and unable to sit still, Ushio heads too. She uses a mask to disguise her and sees how Sou Hishigata gets turned down by Mio and tries to comfort him, but everyone sees through her disguise. Shadow Shinpei appears and captures Ushio and asks her what she was thinking, as she can't trade places with someone who just had a funeral and guesses she had no intention of switching. Ushio awakens and tries to get free from Shadow Shinpei, but tells her she is a shadow like them as a human can't heal a broken arm that fast. Shadow Parent attempts to consume Shinpei, but Ushio comes and punches him, giving time for Hizuru to kill Shinpei and send him back in time.
Ushio appears behind Shinpei while he is making curry, which surprises him and makes him comment that she shouldn't appear until the festival. Ushio tells him that shadow-like monsters ate everyone at the festival and if he too was there. As Mio appears, Ushio hides and soon receive a note from Shinpei to get to his room. There she eagerly awaits for Shinpei's curry and enjoys it while eating it. She explains she woke up at the Omoto beach, but made sure no one saw as they now see her as a monster. The two agree to work together and stop the shadows. Mio comes to pick up the plates and almost sees her. Mio then leaves, but returns few seconds later and again almost sees Ushio. However, this ends up being Shadow Mio, who attempts to kill Shinpei, but Ushio protects him with her body, taking the hit. Mio then stabs her shadow and wounds Ushio. Mio asks Ushio why she protected Shinpei and Ushio explains its because she loves him. Mio attempts to kill Shinpei, but Ginjiro and Shinpei kill her. Ryunosuke comes to kill Ushio, but Shinpei stops her and asks for her help. Ushio wonders if the real Mio is okay and Ryunosuke confirms. As her voice is the same as the one from her message, Hizuru decides to save her.
Once outside, Hizuru pours water on Ushio's arm, which then disappears. Hizuru explains the wound was a projection of the damage done to her main body. Hizuru then shows the message from Ushio, that asks her for help and that Shinpei is the only one who can stop the shadows, but Ushio has no memories of it. Hizuru decides to stop working with Shinpei as he is with Ushio and they don't know when she will be "fixed" and turn against them.
The next day, Shinpei meets with Sou. They go to the beach, where Sou wants to tell him something related to Ushio's death. Ushio then shows up behind him and guesses its the strangle marks, which makes it look like she was murdered. Sou confirms, but then sees Ushio and ends in a shock. After they tell him everything, Sou apologizes for not being able to save Ushio and wants she to punch him. Ushio then kicks him and tells him to get up as they rely on him. Shinpei gives her phone. Ushio sees the password had changed, but her fingerprint unlocks it. She then find a video from the morning when Ushio died. Watching the video, they see Ushio and her Shadow Ushio on it. Ushio tells him that Shadow Ushio is on their side and continues to explain how she met her Shadow and formed a plan to save Shiori. When the video ends, Shadow Ushio regains her memories and abilities and decides to replay them the memory of how Ushio died. She transports Shinpei and Sou on the private beach on 21st. They witness how Shiori is being dragged underwater by her Shadow and Ushio and her Shadow trying to save her. They manage to take Shiori from her Shadow, but Shadow Shiori then strangles Ushio and captures Shadow Ushio. She attempted to fix the faulty Shadow, but Mio and Sou came and she pretended to be the real Shiori, while erasing the real one. While Mio carried Shiori, she grabs Shinpei's arm, surprising him, thinking that was just a memory and they couldn't interact. Shiori then turns to Heine, who states she found him and won't be letting him go. Shadow Ushio ends the replay and Shinpei sees a mark on his hand where Heine grabbed him. Shinpei decides they need to investigate the old clinic.
They go to the old clinic and while looking around, they find an old wood Hiruko statue. Shinpei notices a crack on the wall and asks Ushio to go, who then sees the wall is a secret door but it needs a key. Shinpei figures the Hiruko statue looks pregnant and Ushio scans it, and copies the key from inside. As they open the secret door, Ushio tells them she feels a shadow down below and has a bad feeling. As they go down, they see its an old tunnel dug during the war. Shinpei asks Ushio to prioritize protecting herself and Sou to protect her as well. He explains that if he dies, he will loop, but if Ushio dies first, she may not loop back with him. Heading towards the shadow, they see a baby-like shadow, who appears to be deaf and blind, but manages to smell them. The shadow jumps on Sou, but Shinpei manages to pin it with his nailgun and Ushio kills it. Ushio explains that the first shadow she felt is still down the tunnel and they continue. Ushio realizes that she still haven't recovered from the damage she took from Mio, even though she printed a new arm. They hear a gunshot and end in a natural cave, where they get surrounded by baby-like shadows. As they fight them back and try to escape, Shinpei notices that the shadows are only attacking Ushio. Once they manage to escape, he sees that Ushio isn't well and her wound from Mio haven't disappeared. Ushio then explains that she needs to copy the original to restore the lost data, but as original Ushio is now ashes, she can't heal the wound. Tokiko then appears, thanking them for bringing the defective product, Ushio. Shinpei shoots at her shadow to pin her, but Tokiko laughs and reveals she is human. Having no choice, Shinpei decides they to surrender, figuring that they won't hurt Ushio right away, he wonders if she will take them to her father. As they follow her, she takes them to Hiruko, who Shinpei recognizes as Heine. Tokiko explains that Heine is Hiruko, the god of the island. They bring out Ushio's real body to feed Heine with it. The moment she eats another body and turns to eat Ushio's, Shinpei asks Ushio to print him the nailgun. With it, he frees Ushio, who jumps in and takes Ushio's body. Shadow Ushio then scans Ushio's body, making her able to regenerate her arm. Heine sends a shadow Negoro to fight them, but Ushio kills her. The shadow parent appears and cuts Shinpei's fingers, and holds Mio as hostage. He then kills Sou and Tokiko. Heine decides to reprogram Ushio and starts corroding her. Hizuru comes and manages to free Shinpei, but she also dies. Shinpei then drinks a poison he had on him to kill himself. Ushio starts to resist the corrosion and even turns is against Heine, who then asks the shadow to kill Ushio, but Shinpei dies and loops both of them before they kill Ushio.
Shinpei tells Hizuru everything and believes their mistake was that they all acted separately. Hizuru agrees to work together this time. Shinpei normally wants to go directly for Heine, but they don't stand a chance against the four-armed shadow. Ushio suggests they go after Shiori as she believes she can erase her. While gathering at the Kobayakawa's and Hizuru entering to kill them, Ushio reveals that she can keep her scanned data from previous loops and prints a new nailgun for Shinpei. To their surprise, Hizuru is throw out of the window. She tells them to run, but the four-armed shadow kills her. Heine as Shiori comes and states that ever since she touched Shinpei and left him that mark on his hand, she can easily find him. She also reveals she can also loop and had been going after him since their eyes met on the summer festival. After the shadow kills Ginjiro and is about to capture Shinpei, Ushio beheads Shinpei and scans one of the arms of the four-armed shadow.
While they are looping, Ushio reveals that the shadow had no data and its empty, but kinda smells like Heine. Shinpei and Ushio then end up in front of their house, but soon realize its just Hizuru's memory from fourteen years ago. Soon they end up at the old Hishigata clinic, where Hizuru meets her new friend Heine. Shinpei and Ushio observe Hizuru and Heine, who spend time together. They learn that the four-armed shadow is greed incarnate and is called Shide. One day, Heine loses control due to her hunger and ends up killing Ryunosuke. As Hizuru finds them, Heine regains control and states she didn't do it, causing her to burst and blow out her eye and sends Ryunosuke's data to Hizuru. Heine runs and two stray shadows appear, but Ginjiro protects. The other shadow copies Ginjiro, but Ryunosuke takes over Hizuru and kills the shadows. Later Hizuru leaves the island and Heine promises to kill her when they meet again.
Shinpei loops back while they were heading towards the Kobayakawas, but stops Hizuru and calls off the mission. They go to the elementary school, where they call Sou, Tokiko, Mio and Tetsu and Ushio plays her memory of the past loops to them. Hizuru believes that the shadows will be coming after Shinpei and since Heine knows where he is, they can prepare and plan where they want to fight them. Shinpei speaks in front of everyone and manages to motivate them to fight alongside him, however, Shide then kills Shinpei with a rifle, ending the loop.
Ushio and Mio find Shinpei and explain that he was killed by a sniper rifle, making Shinpei realizes they got Ginjiro. He explains to Ushio and Mio first, and then to everyone that he can only loop one more time as the time limit moves faster with each of his deaths and soon he there won't be a place he can return to.
Shinpei waits outside for Heine and Shide, but as they come and attack him, Ushio takes Shinpei and runs. While others fight them, Ushio and Shinpei manage to lure Heine and Shide to the gymnasium. There Ushio copies gasoline and Shinpei ignites it. Heine jumps to the ceiling, but Shinpei injures her. Ushio then attempts to erase Shiori since Heine was taking her form, but got distracted and Shide grabbed her and pulled her into the fire. At the same time, Shide shot Shinpei multiple times, avoiding vital organs, but ensuring his death in couple of minutes, so that he has time to kill Ushio. However, Ushio was a dummy copy and Ushio appears behind Shide and punches him and start erasing him. Heine then scans and erases the air in the gymnasium, putting out the fire and bursting the windows from the vacuum, allowing them to escape with Shide. Shinpei reveals that he is okay as he had made bulletproof vest. The group had captured shadow Mio and asks Ushio to turn her one of them.
After making Shadow Mio their ally, Shinpei questions her and they learn that all shadows except Heine, can give "birth" to only one shadow and that shadow cannot give "birth". Shinpei then decides they go speak with Seido Hishigata as he seems to know Heine's plan. However, reaching the hospital, they see all items and furniture being erased. Ushio senses a shadow and they follow to the morgue in the basement, but see Ushio's real body is gone. They continue a path leading to Hiruko Cave, but on the way, they see Seido chocked by his wife, Chitose. Ushio then stops her and severs her connection with Heine. After Seido learns he is immune and they can't copy him, he decides to tell them everything and that Shide is Heine's guardian and the first child she gave birth to, Shidehiko Hishigata, the founder of the Hishigata Clinic, as well as its first director.
- The name Ushio means "tide, ebb, opportunity" (潮).
- Ushio's surname Kofune means "boat, small craft" (小舟).
- She is half-french and half-japanese.