Loosely based on the 2012 manga Hiyama Kentarou no Ninshin (ヒヤマケンタロウの妊娠) by Eri Sakai, it tells the story of one man's experience being pregnant.

[1][2][3] He's Expecting follows the story of "Kentaro Hiyama, an elite ad man, [who] suddenly finds out one day that he is pregnant.

Kentaro Hiyama is a 37-year-old advertising executive who has successfully marketed a new campaign for his client called UNIVE, which strives to have the public be more accepting of their looks.

In denial, he hastily buys a pregnancy test which confirms it, before getting a call from his boss, Osugi, telling him that his campaign idea has been accepted, and that he does not have anyone to replace him.

After speaking with her friend, Eri, who has had a baby, despite prior beliefs, Aki attempts to treat her cramps, despite the possible risk of not being able to have children.

Kentaro discovers that his meeting has been moved and Osugi has decided to give the project lead to Masato Tanabe who displays a slightly chauvinistic personality.

While he befriends him, as well as his wife Noriko and their son Takuya, he tells him that he is considering abortion; leaving Shota visibly disappointed.

Aki reveals to one of her journalist friends that she is the mother of Kentaro's baby and he suggests doing a personal story about her life with him as opposed to an open-minded piece.

Kentaro starts to become stressed out by work and tries to resign, but Osugi and the rest of the executives all coerce him into staying with the company.

Aki's colleague offers her a job in Singapore, but she would have to live there for two years, thus she cannot bring herself to tell Kentaro whether she has accepted the position or not.

Kentaro returns home to find Aki who tells him that she will be taking the Singapore job, but that she will continue to be part of the baby's life and will be able to travel back and forth and provide for them.

Kentaro's bosses set up a press conference to clear up the issue regarding Eiichi and gives an impassioned speech about roles which is viewed by everyone.

On April 8, 2021, it was announced that Netflix and TV Tokyo would co-produced a live-action adaptation of the manga series Kentaro Hiyama's First Pregnancy.

[7][8] During the Netflix Festival Japan 2021 livestream on November 10, 2021, lead series director Yuko Hakota revealed that the first season will consist of eight episodes, each with a running time around 23 minutes.