The sixth episode begins with slight unrest in the Yuzuki household. Mikoto and Minato did not come home for lunch, which is unusual, especially for the usually responsible Mikoto. The brothers speculate about their whereabouts, with Gakuto showing a moment of maturity that amuses Hayato.

Minato, still recovering from an illness, reflects on his friendship with Uta and the changes it has undergone due to her new relationship. He ponders the concept of dating, leading to a humorous but misguided attempt to understand it through an internet search. The results of this search convince him that he prefers a platonic relationship.

Mikoto suggests marrying Uta to keep her in the family. This proposal is quickly dismissed by Mikoto, highlighting the brothers' strong familial bond and their lighthearted teasing.

As the day progresses, the brothers return home, and Gakuto's suggestion to cook hot tofu stew for dinner is met with great enthusiasm, even though it's out of season. The meal is intended to aid Minato's recovery. However, Minato is distracted and unable to enjoy the food, as his thoughts linger on Uta's date and the silence that has grown between them.

At school, Uta's unusual silence is noticeable, and Minato grows concerned. He tries to revive their usual camaraderie, but Uta refuses to walk home with him, prompting Minato to reflect on the evolving nature of friendships and the fear of losing precious moments to change.

The narrative takes a poignant turn as Minato begins building their secret fortress alone, a symbol of their friendship that Uta may no longer be part of. In an inner monologue, he questions growing up and the potential loss of happiness and joy.

Unexpectedly, Minato learns from Uta's aunt that Uta has been unusually focused on karate, distracted and seemingly distressed. Minato confronts Uta and discovers that the relationship has ended. Uta's boyfriend had tried to change her, causing her distress. Minato's passionate defense of Uta's true self leads to a cathartic emotional outburst from Uta and strengthens their friendship.

The episode ends with Minato and Uta restoring their relationship and working on the secret fortress together.