Joe is the introverted and eccentric member of the five boys at Hachimitsu Academy, often described as the group’s resident oddball. Socially awkward and perpetually gloomy, he struggles to connect with others both inside and outside his circle of friends. He suffers from severe stomatitis, which results in frequent bloody coughing fits and visible mouth sores. While not debilitating, this condition affects his speech and often disrupts his conversations with sudden bouts of pain or blood.

Despite being the quietest of the group, Joe is also surprisingly lecherous, often making crude remarks and inappropriate jokes in a deadpan tone. One of his most defining quirks is his deep fascination with ants, he keeps an ant farm, names the ants individually, and even claims to be able to distinguish them from one another despite their identical appearance. This odd hobby is treated with an unusual amount of seriousness by Joe and is often used for comedic effect in the series.

Joe is generally loyal and supportive of his friends, though he has moments of emotional distance. After discovering Kiyoshi’s secret escape from the Prison Block, Joe initially shuns him in disappointment. However, he ultimately repays Kiyoshi’s earlier kindness when the latter prevents him from attacking Mari Kurihara, showing that Joe values friendship even if he struggles to express it.

Following their release from prison, Joe experiences a period of depression. As the other boys begin enjoying their freedom and social interactions, Joe still largely isolated feels left behind. In a moment of emotional vulnerability, he even attempts to return to the Prison Block, believing he belonged there more than among the general student body. His outlook begins to shift after meeting Satou, a quiet member of the cooking club, whose presence helps him find renewed purpose and emotional connection.

Jouji Nezu is the shortest and most physically frail among the five boys at Hachimitsu Academy. His gaunt frame, slouched posture, and sickly complexion reflect his poor health, primarily due to his recurring stomatitis. His appearance is further marked by an ever-present hood, which casts heavy shadows over his eyes and most of his facial features, giving him a perpetually gloomy and mysterious look.

Notably, Joe’s hood is a detached accessory, not attached to any particular piece of clothing, allowing him to wear it with virtually any outfit even in the swimming pool. During his incarceration, he wears the standard male prison uniform of white-and-blue striped overalls, always paired with his signature hood.

In one of the group’s schemes, Joe participates in a triple switch involving himself, Gakuto, and Chiyo. As part of the disguise, he impersonates Gakuto by wrapping bandages around his head and wearing glasses, though the effect is more comical than convincing.

Following his release from the Prison Block, Joe resumes wearing the standard male school uniform, still accompanied by his ever-present hood, which remains a constant part of his character design.

Shingo Wakamoto
Among the five boys, Shingo is the closest to Joe, likely due to their similarly blunt and laid-back personalities. The two are often seen spending time together, exchanging dry humor and commentary on the group’s antics. Their friendship takes a brief competitive turn during the cavalry battle, when they develop a short lived rivalry over whose love interest Satou for Joe, and Anzu for Shingo would serve as their team’s cavalry rider. Despite the tension, their bond remains solid throughout the series.

Takehito Morokuzu
Joe shares a long-standing friendship with Takehito “Gakuto” Morokuzu, having known him since middle school. He often jokes at Gakuto’s expense, especially about his infamous pants-wetting incident and his supposed “romantic” dynamic with Kiyoshi. Their relationship takes an unusual turn when Gakuto enlists Joe’s help in understanding Mitsuko Yokoyama’s interest in yaoi. The two stage mock yaoi scenarios to assist Gakuto’s courtship, and Joe becomes unexpectedly invested in the act going so far as to develop a fascination with Mitsuko’s yaoi doujinshi featuring himself and Gakuto. Eventually, Joe distances himself from the doujin and recommits to supporting Gakuto’s more serious plans to rescue the Underground Student Council.

Satou
Satou is Joe’s classmate and eventual love interest. Known for her calm behavior and talent in cooking, she wins Joe’s affection through small acts of kindness, such as offering him cupcakes or mochi snacks. She is one of the few people outside his core friend group to whom he openly admits his obsession with ants. Out of affection and awkwardness, Joe avoids using her real name and instead refers to her with whimsical nicknames like Cake-san, Diamond-san, and Star-san. During the cavalry battle, Joe is dismayed to learn that Satou has a university boyfriend, though this relationship later proves to be troubled and insincere.

Mitsuko Yokoyama
Joe becomes unexpectedly involved with Mitsuko, an eccentric student known for creating yaoi doujinshi, particularly one involving Joe and Gakuto as a fictional couple. When Mitsuko considers destroying her work, Joe intervenes and encourages her to finish it, even taking on the role of her self-proclaimed editor and number one fan. His intense involvement leads to misunderstandings particularly from Gakuto, who misinterprets the nature of their relationship. Eventually, Joe distances himself from the doujin project and instead lends his support to Gakuto’s mission to protect the Underground Student Council.

The given name Jouji (譲二) consists of the kanji 譲 (jou), meaning “yield” or “concede,” and 二 (ji), meaning “two.” The name could be interpreted to suggest “second to yield” or “a yielding second,” which may subtly reflect Joe’s tendency to step back socially or his passive, withdrawn demeanor among the group.

His surname, Nezu (根津), is composed of 根 (ne), meaning “root” or “radical,” and 津 (zu), meaning “harbor” or “ferry.” Together, the name could be read as “rooted harbor,” symbolizing a grounded but secluded nature—apt for Joe’s quiet, introspective personality and limited social interactions.