Danjo no Yuujou wa Seiritsu suru? (Iya, Shinai!!)

Yuu Natsume met Himari Inuzuka in middle school while trying to sell his accessories made with preserved flowers. When Yuu told her about his dream to open a shop to sell his creations, Himari decided to help him. Now, in their second year of high school, Yuu sells his accessories online thanks to Himari modeling and promoting them. As Yuu's best friend, Himari declares that if his ambition does not come to fruition by the time they turn thirty, she will have to marry him herself.

Then, Yuu meets Rin Enomoto, a girl wearing one of his first designs. Yuu and Rin met as children years ago, and she was his first love. Himari pushes them together, hoping to help Yuu out of his creative slump and find a wife for him in the process. For the first time, another person understands Yuu's talent and wants to be friends with him. As Rin and Yuu get closer, however, Himari struggles to keep her feelings for her best friend in check.