Tsubaki has straight, chin-length chestnut hair that curls slightly at the ends. Her hair is parted down the middle, framing her face, and she has glowing brown eyes that add to her warm, energetic appearance.

She is most commonly seen wearing the Sumiya Junior High School uniform, which consists of a blue shirt, a gray blazer, and a short plaid grey skirt. Her outfit is completed with a red and white striped necktie, navy stockings, and brown loafers.

In her role as a softball player, Tsubaki is often seen in her softball uniform, which includes a loose white short-sleeved shirt layered over a red long-sleeved turtleneck. She pairs it with red shorts featuring white stripes on each side. To complete the look, she wears a white baseball cap backwards, tying her hair into a small ponytail.

Tsubaki is a kind, caring, and outgoing girl who is always ready to support her friends in times of trouble. She is particularly protective of her female friends, showing her fierce loyalty, such as when she became upset after Ryota Watari broke up with one of them. Tsubaki is also adventurous and sometimes impulsive, often engaging in risky activities.

Despite her generally calm and kind nature, Tsubaki is easily angered, especially when it comes to matters involving her loved ones. In her childhood, when Kousei Arima was too focused on his piano practice to join her in play, she would make things for him and comfort him when his mother got rid of a cat he had found. Tsubaki is seen as somewhat of a tomboy, with her short hair and love for sports, which has led some classmates to call her “creepy” due to her personality and appearance. This judgment caused her to start doubting herself and thinking negatively about her own image.

Tsubaki has a hard time recognizing her own feelings, especially when it comes to Kousei, her best friend. She would often talk about him, worry about him, and keep an eye on him without fully realizing the depth of her emotions. Her friends, including Watari and Kaori Miyazono, were aware of her feelings for Kousei, even though she kept them hidden. Tsubaki’s devotion to Kousei is evident when, despite her own injuries, she is willing to carry him on her back after he gets hurt.

Though she secretly likes Kousei, Tsubaki lacks the courage to confess her feelings. She often hides her true emotions behind a smile, but her emotional outbursts reveal her inner turmoil. She is deeply possessive of the people she cares about, particularly Kousei, but respects their decisions, even when it causes her pain. Her love for Kousei is so strong that she chooses to attend a high school near his, so she can continue to be by his side.

Tsubaki is highly athletic and has been since childhood. She would often invite Kousei Arima, who was typically absorbed in his piano lessons, to join her in outdoor activities. She would convince him to participate in daring stunts, sometimes even risky ones, which helped shape her adventurous and outgoing personality.

Skilled in sports, Tsubaki is an active and valuable member of her school’s softball team. Her performance on the field is often influenced by her emotions—when she’s angry, she plays with greater intensity and aggression, while sadness tends to cause her to lose focus and miss more shots.

Although she is sometimes seen as a person who struggles academically, Tsubaki surprised her classmates by scoring a B on a particularly difficult , which had been deemed “hard” by all the other students in her class.

Background

Tsubaki is Kousei Arima’s childhood friend, who has always supported him by attending his performances and cheering him on. She frequently invited Kousei to play outside, but due to his rigorous piano practice schedule, he was often unable to join. Over time, Tsubaki naturally took on the role of an “older sister” to Kousei, often caring for him and looking out for him. She saw him as the “hopeless little brother” she had to take care of. Tsubaki would prepare small gifts for Kousei and comfort him during difficult times, such as when his mother abandoned a pet cat he had found and was deeply upset over its disappearance. Unlike Kousei, who was immersed in music, Tsubaki’s passion was always for athletics.

Shigatsu wa Kimi no Uso

In junior high school, Tsubaki is an active member of the softball team. One day, while playing, she hits a softball that shatters the glass window of the music room, injuring Kousei in the process. Upon arriving at the scene, Tsubaki finds Kousei lying motionless on the floor. Panicking, she tries to discreetly retrieve the softball and leave without drawing attention. However, when Kousei stirs and reaches for a shard of glass, Tsubaki immediately stops him, warning him not to touch it in case he gets cut. Just then, Watari takes a photo of them and teases them, adding a lighthearted moment to the tension. Tsubaki and Kousei walk home together, parting ways once they reach their respective houses. Soon after, Tsubaki receives a phone call.

Kousei Arima

Kousei has been a close friend of Tsubaki’s since childhood. As neighbors, they share an extremely close bond, with Tsubaki constantly worrying about him and feeling the need to look out for him. Initially referring to Kousei as her “kid brother,” Tsubaki later realizes that her feelings for him have deepened beyond friendship. She is heartbroken when she believes Kousei will leave her to pursue his dream of becoming a pianist. However, after Kaori’s death, Tsubaki decides to stay by Kousei’s side, supporting him as he navigates his emotional struggles.

Ryota Watari

Watari is another childhood friend of Tsubaki’s, and the two share a strong connection through their mutual love for sports—Tsubaki plays softball, while Watari plays soccer. Watari is particularly perceptive about Tsubaki’s feelings, having realized her unspoken love for Kousei long before Tsubaki herself acknowledged it. Watari’s understanding of Tsubaki’s emotions makes him a valuable friend and confidant.

Nao Kashiwagi

Nao is one of Tsubaki’s closest friends and confidants. Nao is highly observant, often picking up on Tsubaki’s emotions before others do. She notices how Tsubaki uses her relationship with Saitou as a way to hide her true feelings for Kousei. Although Tsubaki initially brushes off Nao’s advice to be honest with herself, she eventually comes to terms with her feelings and follows Nao’s guidance.

Kaori Miyazono

Kaori is Tsubaki’s classmate and friend, though unbeknownst to Tsubaki, she is also a love rival for Kousei’s heart. Despite Kaori’s feelings for Kousei, Tsubaki remains unaware of the romantic tension between them and maintains a close, friendly relationship with Kaori.

Saitou

Tsubaki frequently communicates with “Saitou-senpai” through messages and phone calls. She initially uses her relationship with him as a way to mask her true feelings for Kousei. Although Tsubaki develops some genuine affection for Saitou, her love for Kousei eventually becomes apparent, leading to their breakup. Their split is further complicated by their similarities and Saitou’s growing interest in the manager of his baseball club.

• (Monologue) “Everyone was stepping boldly one foot at a time… while cheering themselves up, while being provoked, while being supported, trying to advance. I was the only one not stepping forward. I wish time would stop. The only one whose time had stopped… was me. I want to advance. I want to step forward. I want my time to move.”

• (To Kousei Arima) “You do too have a soul, Kousei. It’s just that you’re good at hiding it. So good, you can’t even find it yourself. So I’m going to find it for you. So you won’t lose your way, so you won’t have regrets… I’ll stay by your side forever. After all, I know everything there is to know about you.”
• (Monologue) “Even though I’m upset that I lost… Even though I’m depressed… Even though my ankle hurts and my eyes are stained with tears. I don’t think I’ve ever felt worse. So why do the stars look so bright tonight? The scent of the music room in his hair. The sound of his slightly ragged breathing. His shoulder, warm and wet with tears. I am by his side. I wish we could live in this moment forever.”
• (Monologue) “I’m discovering all these different sides of myself that I never knew I had… Facing all these different sides of me. I guess that’s also… What you call… being in love?”
• (To Kousei) “Who cares about music? Who cares about words? We have all the time that we’ve spent together. All those precious memories of all the little things.”