The film opens with an ad for the virtual reality world of “U”, where users can reinvent
themselves into someone they never could be in the real world. Amidst the vast and
expansive digital world, there is a pink-haired singer called Bell, singing the song “U” as
a crowd of users cheer her on and are amazed by her voice as she rides a large flying
whale. In the real world, Bell is meek teenager Suzu Naito.
Sometime earlier, Suzu was just an ordinary girl that nobody paid attention to. Her only
friend is Hiro Betsuyaku, while Suzu has a crush on her childhood friend Shinobu
Hisatake. They also notice Ruka Watanabe, the most popular and beautiful girl in
school, whom Suzu thinks Shinobu is interested in. Another student, Shinjiro Chikami,
or “Kamishin”, tries to get others to join his canoeing club, as he is the only member.
A flashback shows that Suzu used to be close with her mother as a child. One day
during a storm, a little girl got stuck in the middle of the lake atop a small rock pile.
Suzu’s mother went out to rescue the girl and put her life vest on her, but Suzu’s mother
never returned. As Suzu called out in desperation to her, Shinobu was there for her and
vowed to protect her. Now she lives with her father but has since resented her mother
for sacrificing herself to save another person’s child and abandon her own. She also
used to sing, but has since then found herself unable to do so, even with the choir
women that used to be friends with her mother.
Per Hiro’s suggestion, Suzu tries out U for the first time. She takes a picture to scan for
her avatar, but the closest one she has is a group photo that Ruka invited her to be in.
She thinks that the app has scanned Ruka’s face, until she notices the avatar has
freckles just like Suzu does. She decides to name the avatar “Bell”, since that’s what
Suzu’s name means. As she enters U, she is stunned by the world’s appearance, before
she begins to sing for the first time in ages. Some of the other users look on in interest,
while others shrug her off or find her annoying. A small angel-ghost being with a visible
heart flies to Bell and tells her she is beautiful and a great singer. When Suzu logs out,
she is surprised that she was able to sing again.
Bell attracts millions of followers and comments within days, mostly praise but also
others who criticize her appearance and singing. Others call her “Belle” since it means
“beautiful” in French. Suzu runs to Hiro, who is the only one that knows she is Belle, and
while Suzu freaks out over the criticism, Hiro encourages her to keep it up. Soon, Belle
gains millions and millions of followers. Meanwhile at school, Shinobu keeps trying to
talk to Suzu, but she just walks away from him out of shyness since she thinks Ruka is interested in him.
Suzu enters U as Belle to perform for the other users, when suddenly a mysterious
creature-like entity called “The Dragon” emerges. A team of U vigilantes led by Justin
come out in an attempt to subdue Dragon, but he is incredibly powerful and fights them
all off, causing their avatars to be frozen. Dragon manages to escape Justin and flees,
but he leaves Belle interested and curious in his identity.
The Dragon becomes a major sensation on U, with many seeing him as iconic, while
others are unhappy with the way he comes out of nowhere to attack. Suzu and Hiro do
some investigating into his true identity, going off of certain clues, like that he has
bruises on his back. They suspect a reclusive artist named Jellinek, who claims that the
bruises he has are tattoos in memory of his late girlfriend, while a baseball star is also
suspected, but he says the scars on his body are from surgeries. Everyone in U is trying
to locate Dragon’s castle, but nobody has been able to find it.
Belle later finds the angel avatar and is able to locate Dragon’s castle. Although Belle
offers her help, the Dragon wants none of it and orders her to leave. When she is
heading out, she is found by Justin and his goons. They attempt to coerce her into
revealing where she was going, but Dragon swoops in and rescues Belle before Justin
can get what he wants. Over time, Suzu feels that she can get through to Dragon with
her songs, and so she writes a new song and sings it to him as Belle. They have a
ballroom dance together, and Dragon begins to put his trust into Belle.
Ruka contacts Suzu and asks to talk to her. The two bond as friends, and Suzu learns
that Ruka actually has a crush on Kamishin, not Shinobu as she had previously thought.
When Kamishin comes around, Suzu is able to get them together so they can admit
their feelings for one another.
Suzu is then alerted that Justin has found Dragon’s castle. He and his goons begin to
destroy it, while the rest of U looks on. Belle enters and is caught by Justin, who
threatens to use the light from his suit to unveil her true identity to the world, but Dragon
saves Belle again. This prompts Suzu to get help from Hiro, Shinobu, Ruka, and
Kamishin to help find Dragon’s true identity once and for all. Searching through Hiro’s
extensive amount of open windows, they find a young boy named Tomo singing one of
Belle’s songs. Suzu recognizes him from news reports, with him having said Dragon is
his hero. She remembers him and his older brother Kei being with their father, who says
that they are moving on after the death of the boys’ mother. Suzu thinks Tomo is too
young to be Dragon, until they watch on his webcam to find Kei coming in to protect
Tomo from their father, who abuses them. Suzu realizes that Kei is Dragon. She
attempts to reach out to him and say she is Belle, but he thinks she is just one of many
people who are out to mock and hurt him, so he disconnects the camera.
Shinobu tells Suzu that she has to reach out to him not as Belle, but as herself. Despite
Hiro’s protests, Suzu finds the courage within herself to enter U. She finds Justin and
uses his light to unveil herself before the entire world. She begins to sing a song to
reach out to Kei, which eventually everyone in U joins along with as they are moved to
tears. The flying whale comes back to guide Suzu, and eventually, Kei turns his camera
back on. He is ready to trust Suzu, but the father comes back and shuts the camera off.
With help from Ruka and Kamishin, they are able to find from looking outside the boys’
window that they are located in the Kanagawa prefecture near Tokyo.
Suzu takes a train to the city and manages to find the boys’ apartment. On the way
there, she talks to her father, who acknowledges how much her mother’s death affected
her, but he knows she is strong enough to do the right thing. She is found by Tomo and
Kei in the streets, but the boys’ father attempts to violently grab them. Suzu protects the
boys and endures the father’s attempts to grab them, even him scratching Suzu’s face,
but when he appears to try and strike her, she defiantly stands in his face, and he can
do nothing but back down and run back into the house. The boys thank Suzu for her
help and for going as far to help them as she did.
Suzu returns home and is greeted by her father. She reunites with her friends, and
Shinobu says that he no longer feels the need to protect her since she has proven to be
capable herself, and they can resume their friendship, and perhaps something more.
Everyone looks to the sky as a light shines down on them, with Suzu seeming to think it
is her mother looking upon her. She then joins her friends and the choir women as she is ready to sing again.