Satoshi Yabe is a 23-year-old elementary school teacher and homeroom instructor for class 6-3 at Kamohashi Elementary. His students, especially the Marui triplets—Mitsuba, Futaba, and Hitoha—routinely involve him in misunderstandings and chaotic incidents. Students call him "Yabe-sensei" or "Yabecchi," a nickname coined by Mitsuba Marui on his first day.

He typically wears dress shirts, t-shirts, or button-ups with a tie, and is notably associated with a red shirt featuring the word "Cherry." Good-natured and humble, his personality also carries naivety and immaturity stemming from a sheltered upbringing, leading to frequent disrespect from students and colleagues. Despite this, he dedicates himself to teaching, sacrificing personal time to support students like the Marui triplets, even facing ingratitude or confrontations from their father.

Resilience defines him. He weathers mental strain and recurring misunderstandings, persisting in building student relationships. He gradually accepts Hitoha Marui’s habit of hiding under his desk, silently making space for her by the second season. His development shifts from an initially enthusiastic, cheerful teacher to one more resigned and unsurprised by classroom absurdities, particularly in the manga where he becomes easily irritated yet remains professionally committed.

Relationships drive his character arc. With Hitoha, interactions center on a shared fandom for *Gachi Rangers*, though frequent misunderstandings plague their conversations. After Hitoha openly admits her love for the show in *Zōryōchū!* Episode 8, their bond strengthens, leading her to visit his apartment to watch episodes or play related games. She possesses his home phone number and a duplicated apartment key, signaling unexpected trust despite her outward annoyance. Hitoha demonstrates concealed care, consoling him after false accusations or nursing him during illness, though he often misinterprets her actions.

With Mitsuba and Futaba, he develops tolerance for their antics. Mitsuba views him as a "lousy bum" and shows little consideration, while Futaba, the nicest triplet, inadvertently causes trouble through over-zealousness. Early on, the sisters attempted to set him up with school nurse Aiko Kuriyama, whom he admires. His feelings remain unrequited due to his clumsiness and her misinterpretations of his actions, which later shift from indifference to active dislike.

Professionally, he struggles with classroom management. Students often ignore him during lessons, and he experiences jealousy toward peers like Shinya Sato, who attracts female attention. He claims rapport with all students but is closest to the Marui triplets, addressing others formally by last names, creating distance. His aspirations include becoming "the best teacher ever" and finding romantic love, noted in his character song.

Running gags involve confrontations with the Marui sisters' father, who mistakes him for a pedophile, and his victimization in accidental pervert scenarios. One incident saw him awakening feverish to find himself painted with kanji and his boxers placed on Hitoha’s head, further damaging his reputation with Kuriyama. In *Zōryōchū!*, his fandom surfaces when he attends a *Gachi Pink* autograph session dressed resembling *Pokémon*'s Ash Ketchum—a pun on his first name, Satoshi.

Across media, his growth is subtle but evident. He transitions from panic and idealism to weathered adaptability, yet his core dedication to students endures, particularly in his evolving, albeit fraught, connections with the Marui family.