The series begins with first-year student Umika Konohoshi expressing her fear of fitting in at her new school, Fujinomisaki High. She feels isolated and believes her words won’t reach anyone in the world. During the entrance ceremony, she meets her homeroom teacher, Akane Emihara, and struggles with her self-image. Umika wishes she could communicate with aliens, convinced they would understand her.

Unexpectedly, a new student named Yu Akeuchi arrives late to the ceremony and claims to be an alien. Curious but skeptical, Umika tries to approach Yu with an alien language dictionary but lacks the courage. Yu senses Umika’s feelings through a special ability she calls "foreheadpathy" and assures her that she truly is an alien.

The two girls are paired up for a scavenger hunt in class. During this opportunity, Umika shares her dream of building a rocket to find aliens as friends. Yu is moved and reveals that she also wants to travel to space. They decide to work together to fulfill their shared dream.

Later, Yu invites Umika to her home, which turns out to be an abandoned lighthouse. Yu confesses that she has no memories of her life before arriving on Earth and shows Umika her "space travel diary," which ends abruptly. Despite this, Umika promises to help Yu return to her home planet.

The episode ends with the two girls solidifying their friendship and their commitment to their shared goal of reaching space.