Goro Zaizen and Shuji Satomi are assistant professors at Naniwa University Hospital. Goro is a brilliant surgeon who will do anything to make his way up the corporate ladder. On the other hand, Shuji is a physician who earnestly devotes himself to medical research. Though the two doctors have contrasting personalities and are considered to be rivals, they highly recognize each other's skills. The entire medical department is restless while preparing for the election to choose a new Surgical Department Professor. All Goro has on his mind, is how to win the election. Meanwhile, Shuji is looking after a patient who apparently has pancreatic cancer. He carries out tests on the patient cautiously, and is very careful in telling the patient of the cancer. However, Goro barges in on their conversation, and out of the blue, tells the patient he has cancer, and that he needs an operation right away. Shuji is furious at Goro's rude attitude, and yells, "Doctors are not God!" Goro ignores this, and starts laying the groundwork for the operation. But when Goro finds out that the Director of the Medical Department has already given a diagnosis of stomach cancer, he cancels the operation. He feels that pointing out his boss's misdiagnosis will only hurt him in the upcoming election. Shuji however, is determined to save the patient's life and go on with the operation.

Blessed with good looks, Takano Kyohei, a college student, is always suffering from the unreasonable behaviour of customers who want him and the sexual harassment of his store manager. Because of his hot temper, he loses his head on this occasion and is fired from his part-time job. Then one day, the glamorous owner, Ms Nakahara proposes, "I'll give you free board-and-lodging if you can turn my niece, Sunako, into a lady!" Kyohei and Toyama Yukinojo, Oda Takenaga and Morii Ranmaru, the other guys living together in the same boarding house, are enthusiastic, but the person who appears before the four of them is a spooky girl whose hair covers her face and who loves horror and vampires. And so, their tumultuous communal life begins.

Adapted from the manga "The Wallflower" (ヤマトナデシコ七変化) by Hayakawa Tomoko (はやかわともこ).

Yoshiko Aoi is a budding researcher in ethology, the study of animal behavior. "Men=male" are born unfaithful. But through her studies, Yoshiko learns it's not the males' fault. Rather, it's the fault of their genes, who work to replicate themselves by controlling the males' body. This is the sad, but commonly accepted theory of biology. What's even sadder is that Yoshiko's nickname is "Gene," because her name written in Chinese characters can also be read as "Jinko/Geneko." The love story follows Yoshiko's struggles with research and romance.

Hirabayashi Takuto lives with his two friends Hano Kyohei and Okayama Hajime at a share house. They have been friends since high school. Takuto Hirabayashi now works at a company, Kyohei Hano works at a trading company and Hajime works for an apparel brand.

One day, Takuto comes home from work and finds a baby sleeping in the room. Kyohei and Hajime also come home. They read a letter on the desk that says “the baby is yours.” Who is the baby’s father? All three are not very responsible and guess that one of the other two guys is the father. At that time, they notice the baby has a fever.

This second season of Hana Yori Dango picks up right after Domyoji leaves for New York. After confessing to Domyoji, Makino has not spoken to him for a year. Rui and the other members of F4 try and help Makino meet Domyoji again by going to New York for the christmas holidays. Though F4 and Makino meet Domyoji again, he has become a completely different person, and so they leave for Japan.

Some time later, Domyoji's mother annouces that they will be returning to Japan. There, they hold a giant super-rich and classy birthday party for Domyoji and announce something very important. Domyoji, like in the first season, is engaged to a rich girl and heir. The only difference is that they are to be wed soon. What will Makino do?

On the side, Rui begins to fall in love with Makino... will this become a love... square?