"Kimi no Koe o Todoketai" centers on a group of high school students who form a radio broadcasting club to share their voices with the world. The protagonist, Haruka Serizawa, is a reserved and introverted girl who struggles to express herself. After discovering an old radio transmitter, she becomes inspired to create a radio show, hoping to connect with others and overcome her own insecurities. Alongside her are classmates who each bring their unique personalities and challenges to the group, including the confident and outspoken Yui Nakamura, the tech-savvy but socially awkward Riku Takeda, and the thoughtful and supportive Aoi Miyamoto.

The narrative explores their journey as they navigate the technical and emotional hurdles of producing a radio program. The students face obstacles such as limited resources, school regulations, and personal doubts, but their shared passion for communication drives them forward. Through their collaboration, they learn to articulate their thoughts, confront their fears, and build meaningful connections with their listeners. The radio show becomes a platform not only for their voices but also for the stories of their peers, addressing themes of loneliness, friendship, and self-discovery.

As the series progresses, the characters grow individually and as a team, with their efforts culminating in a live broadcast that tests their resolve and unity. The story emphasizes the power of communication and the impact of sharing one's voice, both literally and metaphorically. The characters' development is intertwined with their experiences in the club, highlighting the transformative potential of creative expression and mutual support. The series concludes with a sense of accomplishment and hope, as the students reflect on how far they have come and the connections they have forged through their shared endeavor.