Hinata Tachibana, often called Hina, is the primary impetus for the story's central conflict and the object of Takemichi Hanagaki's unwavering devotion. Her background is rooted in a single, formative childhood event. When she was young, Hinata stood up to bullies who were tormenting a cat and was saved by Takemichi, an act of impulsive courage that made her fall in love with him. This event also inadvertently created a dangerous obsession in a classmate, Tetta Kisaki, who was present and developed a jealous grudge against Takemichi for winning her affection. In the original timeline, Hinata, along with her brother Naoto, is killed in a conflict involving the Tokyo Manji Gang, a tragedy that sets Takemichi on his path of time travel.

In terms of personality, Hinata is characterized as a genuinely cheerful, kind, and optimistic individual. She has a natural warmth that allows her to make friends easily and bring light to any situation. Despite her gentle and caring nature, she possesses a remarkably strong will and is unafraid to act decisively, even with violence, when she feels it is necessary. For instance, she has physically struck both Takemichi and the fearsome Manjirou Mikey Sano in moments of misunderstanding or anger, revealing a fierce and intimidating side beneath her pleasant exterior. Her most defining trait, however, is her profound strength of character and determination, which closely mirrors that of Takemichi. While she is not a skilled fighter, her courage is absolute, allowing her to stand up to dangerous delinquents to protect those she loves.

Hinata's central motivation is her love for Takemichi and her desire to support him, even when she does not fully understand his actions. She is a deeply loyal and understanding person who wants to help her friends and family. Her role in the Tenjiku Arc is pivotal and cements her status as more than just a damsel in distress. After the devastating death of Emma Sano, both Mikey and Draken have lost their will to fight, leaving Takemichi in a desperate situation. It is Hinata who steps into this emotional void. Using her sincerity and strength, she speaks to them and successfully reignites their fighting spirit, motivating them to return to the battlefield to help Takemichi. Her act of courage directly impacts the outcome of the conflict.

Several key relationships define her place in the world. Her bond with Takemichi Hanagaki is the emotional core of the series; she is his first and only love, his greatest source of support, and the reason he continues to fight against fate. She shares a close protective relationship with her younger brother, Naoto Tachibana. She also forms a strong friendship with Emma Sano, initially becoming jealous after misunderstanding Emma's relationship with Takemichi, but later developing a genuine and supportive bond. Her relationship with Tetta Kisaki is one of a childhood crush who became a dangerous, unrequited admirer; his obsession with her is the root cause of most of the story's tragedies.

While Hinata does not undergo a dramatic personality transformation, her development is seen in her growing agency and her evolving understanding of Takemichi. In earlier timelines, she is often confused by his erratic behavior. However, by the Tenjiku Arc, she is capable of taking immense, decisive action to support him by confronting his allies. Furthermore, her development is tied to the revelation of the time travel; at one point, she discovers that Takemichi is a time leaper and that her own death in the future is the catalyst for his journeys. Regarding abilities, Hinata possesses no physical combat skills. Her notable ability is her incredible determination and her powerful, encouraging words. She is able to comfort and motivate others, lifting them from despair and pushing them to take action when they are at their lowest.