Twelve-year-old Hiroshi Tanegashima journeys to the Anshin space station with his older sister, Mina Misasa. Their trip is part of a Deegle corporation-sponsored campaign for underage space experiences. Hiroshi and Mina carry different family names because their parents divorced.

Unlike Mina, who visits reluctantly for social media content, Hiroshi burns with genuine enthusiasm for space exploration. His inquisitive nature shows in his deep knowledge of conspiracy theories. He actively explores the station using augmented reality cyber glasses, leveraging this technology to navigate and understand his surroundings.

Hiroshi idolizes Touya Sagami, one of the last surviving children born in space, and considers himself a devoted fan. This admiration influences his actions within the group during the station crisis caused by a comet strike.

Amidst the escalating dangers, Hiroshi contributes to the group's survival efforts. His fear sometimes manifests as humor, like joking about needing space diapers after a scare—echoing his sister's earlier sarcastic comment about their intended short stay.

Born on Earth, Hiroshi's passion for space contrasts with the space-born children's physical limitations, though he avoids their specific medical challenges. Within the ensemble, he contributes technological insight drawn from his conspiracy knowledge while displaying relatable pre-teen reactions to life-threatening events.