Arihito Atobe is the central character of the series, a former Japanese salaryman who worked in corporate web design. He died in a bus crash while on a company trip and was subsequently reincarnated into a world known as Labyrinth Country, a realm populated by other reincarnated individuals. Upon arriving, he was one of thirty people to be reincarnated, including his former boss, Kyouka Igarashi. In his past life, Arihito was an orphan who lost his parents in an accident as a child and spent time in a care facility, where he once had a dog. Before his death, he held the position of Assistant Manager in the newly established Media Strategy Section 2.

In terms of personality, Arihito is often described as having a tired appearance, reminiscent of his former life as an overworked employee. He is a calm and analytical person, self-aware enough to recognize that he is better suited to observing and supporting from behind than taking the lead in a fight. This thoughtful nature carries over into his role as a leader, where his primary motivation is to protect his party members without exception, stating clearly that this is his present job. While he leads a party composed mostly of younger women, he maintains a gentlemanly demeanor and does not pursue physical relationships with them, despite finding himself in close quarters at times.

His motivations for choosing his unique path are rooted in practicality and a bit of cleverness. Aware that the support position of a rearguard is dangerous and therefore unpopular, he saw an opportunity to attract skilled front-line fighters to his party. Instead of selecting a traditional rearguard job like Priest or Wizard, he simply wrote Rearguard on his license, hoping to force the system to grant him the role. This gamble succeeded, but the job's name appears as unreadable random characters on other Seekers' licenses, marking it as something unique.

Arihito's role in the story is that of the party leader and primary support. He is a Seeker, an adventurer who explores labyrinths. His abilities as the Rearguard make him arguably the most powerful support character in the world, allowing him to empower his allies significantly from the back line. He is known for his rapid rise in the districts, advancing much faster than any Seekers in history, which earns him nicknames such as the man in a suit and Nova from the guild administration. One of his most notable abilities is that he can equip any weapon, a skill usually reserved for the Weapon Master job, and he often uses a slingshot to channel his magic.

His key relationships include his party members, all of whom are younger women, as well as his former boss, Kyouka Igarashi. She expected him to work with her again in the new world, but Arihito declined due to his knowledge of her demanding nature, leading her to vow that he would regret the decision. He also shares a unique bond with his party, and his skills are designed to work in tandem with them. For example, his abilities include Attack Support to add injury points or weapon attacks to his party members, Defense Support to reduce damage they take, Recovery Support to heal them over time, and Charge Assist to transfer some of his magic to an ally. His Morale Discharge ability, Complete Mutual Support, widens his support range to the entire party and any sub-party, applying all individual buffs to everyone for a limited time.

Throughout the story, Arihito develops from a tired, reclusive salaryman into a confident and capable leader. He is not a frontline fighter but rather the strategic cornerstone of his team, whose power is measured by the strength he gives to others. His unique class continues to grant him new and powerful support skills as he levels up, such as Outside Assist, which allows him to support a target outside his own party.