Shinsuke Kuwano, a successful architect at 40, enjoys living by himself. He doesn't like people but somehow is able to design wonderful houses for them.

He has a routine of making himself a delicious dinner and then relaxing to classical music in his easy chair while pretending he is the conductor. One night, he plays the music loud enough to make his next door neighbor, Michiru Tamara knock on his door to complain. When Kuwano answers the door, he suffers a terrible stomach pain and collapses to the floor. Lucky for him, Michiru is nice enough to accompany him to the hospital, where he is treated by Dr. Natsumi Hayasake. He is really rude to Natsumi, but she is still determined to treat him.

Afterwards, Michiru and Natsumi become part of Kuwano's life. They make friends with Kuwano's colleagues Eiji and Maya Sawazaki. They all enjoy talking about how strange and eccentric Kuwano is. Is it possible that someone would ever want to marry him?

Kekkon Dekinai Otoko (lit. The Man Who Can't Get Married) original series from 2006 continued thirteen years later in 2019 with second season titled Mada Kekkon Dekinai Otoko (lit. The Man Who Still Can't Get Married).