真名美小时候参加父亲的拳击比赛，对他深红色拳击鞋留下深刻印象，她的父母后来不幸在事故中丧生。真名美独自扶养女儿爱米，丈夫因病去世后，她决定追随父亲脚步，重返拳击场。她的身心并未准备好，因为贫困女儿监护权落到岳母手上，愤怒又悲伤的她陷入低谷，教练却承诺让她成为拳击冠军，与女儿重逢。

As a child, Manami attended her father Takuma's boxing matches and marveled at the scarlet shoes he wore. Unfortunately, he and his wife died in a terrible accident while he was preparing for the long-awaited championship. Now a single mother of a daughter she adores, Emi, Manami has decided to follow her father's footsteps and is back in the ring after her husband died of a long illness. However, her mind and body are not there and she is humiliated. Sinking into poverty, barely able to feed Emi and losing every job she has, her mother-in-law gains custody of her daughter. Overwhelmed by grief and anger, unable to catch her breath, she falls to her lowest point. However, her coach comes to pick her up from the Fukuoka Red Light and promises to make a champion of her so she can reconnect with Emi.

娘と二人で、慎ましくも静かに暮らす真名美は、ある日家庭裁判所に呼び出された。女子ボクシングに打ち込む真名美たちの経済状況が悪く貧困状態にあり、娘を義母が育てるべきだという行政の判断に押され気味だ。そんな中、正義感の強い真名美は職場で理不尽な目に遭っている同僚を庇ったことで失業してしまい窮地に陥る。だが、周囲の支えにより新たに老人介護施設での仕事を得るが、そこである事故を起こしてしまい、娘と一緒にいられない状況になってしまう。娘を取り戻すためには、ボクシングの試合に勝ってファイトマネーを得て、生活を立て直すしかない。最強のチャンピオンへの挑戦―――。もう真名美には試合に勝って奇跡を起こすしかなかったが。。。