While reminiscing about her journey so far, Aoi Yukimura finds herself eager to go mountaineering once more. A likely opportunity arises when Koharu Senjuin invites Aoi to check out the Mountaineering Club after school. As the head of the club, Koharu speaks enthusiastically of the activities she and the other members partake in, especially as they strive to reach the top in various competitions. Although impressed by the club's dedication to its goals, Aoi feels reluctant to join, preferring to learn and enjoy mountaineering at her own pace. Her experience during this brief visit, however, leaves her wondering why she climbs mountains in the first place. With the support of her friends, Aoi searches for the true motivation behind her hobby, all while continuing to train for the highly anticipated second trip to the summit of Mt. Fuji.

For generations, the Bernstein family has been recognized as a house of nobles who favor books over everything else. Elianna Bernstein, daughter of a baron of the Sauslind Kingdom, is no different. But instead of being called a bookworm, she is known as the Bibliophile Princess. Four years ago, the crown prince, Christopher Selkirk Asherald, offered Elianna a special arrangement: if she would become his fiancée, he promised that she could continue to spend all her free time reading. Despite having to inherit a title of great responsibility, she agreed to the proposal, enticed by the prospect of gaining access to the royal archives housing a wide selection of books. To this day, Elianna firmly believes that her engagement is void of romantic sentiment. When she notices Christopher's interactions with another girl, she presumes that the days she spends with him will soon reach an end. Yet, during this period of uncertainty, Elianna and Christopher open a new chapter in their relationship, gradually uncovering their genuine feelings as they grow to better understand each other.

Third-year high school student Jirou Yakuin is in love with his childhood friend and classmate, Shiori Sakurazaka. Thus, he hopes to be paired with her for the "marriage practical": their school's practice of randomly selecting boy-girl pairs to live as pretend married couples while monitoring and rating them on how close they have gotten. Meanwhile, the lively Akari Watanabe wants to be assigned to her crush, the popular and good-looking Minami Tenjin. Much to their dismay, Jirou and Akari find out that not only have they been paired together, but so have Shiori and Minami! Determined to be with their crushes, Jirou and Akari strive to earn as many points as possible, as the top 10 pairs earn the right to switch their partners—so long as both couples agree.