I Give My First Love to You

Mayu and Takuma become friends at age eight. Takuma suffers from a heart condition and is treated by Mayu's father, a cardiologist. They overhear that Takuma may not live past twenty, and they vow to marry when they turn twenty.

As years pass, Takuma learns his days may be numbered and resolves to distance himself from Mayu after his last day of junior high. He hopes to spare her pain by stepping away and pursues a future elsewhere.

Mayu enters an elite high school and shines as the first-year student body representative. In the school hall, she scolds Takuma, insisting that his plan to abandon her cannot succeed. Their relationship becomes a visible, whispered romance among the students.

Despite his intention to withdraw, Mayu and Takuma’s bond remains strong, and they are soon known around the school as a couple. They share quiet moments that reinforce their commitment. The school community watches their romance with a mix of awe and tension.

Kou confesses interest in Mayu and asks her to be his girlfriend, but she declines. Meanwhile Takuma meets Teru, another heart patient, and Mayu grows jealous as Teru spends more time with Takuma.

Kou asks Takuma to step aside, but Takuma refuses. To honor Teru's dying wish, Takuma shares a kiss with Teru, which triggers a temporary rift between him and Mayu. Their bond endures despite the tension.

The day after the kiss, Teru dies, leaving Takuma shaken and more determined to protect Mayu's happiness. He carries Teru's memory as a quiet weight. Mayu's jealousy softens in the wake of Teru's loss.

Takuma challenges Kou to a 100-meter race and wins, sparking a renewed rivalry. On the same day, Kou leaves the school with Mayu and Takuma and is struck by an oncoming train. The accident profoundly alters the course of their lives.

Takuma learns there is a suitable donor heart available. Mayu discovers the donor is brain-dead Kou and tries to shield Takuma from the truth. Kou's family, moved by tears, refuses the donation, hoping for a miracle instead.

Takuma suffers a heart attack and medical odds look bleak. In a miraculous moment, he prays for more time and unexpectedly recovers. He later takes Mayu on a honeymoon across various places to celebrate life.

During the honeymoon, Takuma expresses gratitude and happiness with life, handing Mayu his written 'will.' They revisit the field where they first kissed to mark the moment and seal their renewed bond.

Back at the hospital, Takuma suffers another heart attack and dies despite the doctors' best efforts. Mayu is left to cope with the loss and the weight of their shared promise.

Mayu reads Takuma's final letter on the hospital rooftop, then goes to a church with his urn to perform a symbolic wedding. The ending flashes back to the first moment they met in the hospital when they were eight, completing the circle of their story.