When Santaro Ishihara (Yo Oizumi), a just-fired supermarket salesman, arrives at the Sakuragaoka Sogo Hospital, three young patients have hijacked the broadcasting studio and are blaring dance music throughout the wards. It is their rebellious tribute to a just-deceased friend.

Unperturbed by the thorny welcome, Ishihara accepts a job to teach at the inhouse school. His students suffer serious illnesses like leukemia, kidney disorders, asthma and diabetes. Confident of the curing powers of laughter, Ishihara walks into class wearing a clown's red nose and proceeds to unleash jokes and gags. Two boys walk out of class in disgust.

The complicated attitudes of teenagers battling disorders aren't the only challenges facing Ishihara. There's the hard-nosed pediatrician Haruka Nanase (Yu Kashii) who believes the children need medical treatment above all else and wants to shut down the school. Ishihara's supervising teacher (Satomi Kobayashi) also looks askance at his bumbling antics to win over the children since she has carefully developed a trusting relationship with the patients and doctors. "Akahana no Sensei" follows the journey of Ishihara as he tries to convey his faith in optimism to his students while he also learns from them about their own coping methods with their illnesses. The drama deals with the heavy themes of sickness and death, dreams and reality and the limits of modern medicine. But the comic antics of Ishihara, the cool sarcasm of his opponents and the uplifting acting of the young patients make “Akahana no Sensei” a heart-warming, inspirational and, at times, hilarious drama.

这部剧以医院内的学校为背景，讲述因为患病而不能正常上课的学生和在那么任教的老师及小儿科医生之间的故事。

本为售货员的石原参太郎（大泉洋饰）刚被辞退了。就在这时, 他被介绍到樱山综合医院来当院内学校的老师。

病童之中, 有患上急性骨髓白血病, 慢性肾炎, 哮喘及糖尿等等的病。参太神一向相信开朗的心境及笑容是医治疾病最好的良方, 于是参太郎决定套上红色的鼻子进入教室且说出很多的笑话来令课堂的气氛变得轻松。可是立即就有两位男生因为讨厌他的教法而走出课室。

而参太郎面对的困难不只是来自病童, 还有来自非常认真，非常冷静沉着的年轻小儿科女医生、七濑遥华（香椎由宇饰）。她认为对病童来说, 把病医好比起其它任何事情更重要, 所以她一直都想把院内的学校关闭。而当小学部教师的太川绢（小林聪美饰）对参太郎的做法抱有怀疑的态度。

参太郎一方面努力将乐观的信息传递及病童, 另一方面他也从病童身上明白到他们如何面对及对抗病魔。

本剧的内容虽然涉及生与死, 梦想与现实, 医疗的界限等等沉重的话题, 但是另一方面因为主人公用乐观的心态去面对人生, 而令本剧也有轻松及感人的一面。