Boxxo is the main protagonist of his story, a character whose very existence is defined by an unusual and ironic transformation. In his previous life, he was a Japanese man with an all-consuming passion for vending machines, an obsession so profound that it ultimately led to his demise. He died in an accident while trying to save a vending machine from falling off a truck, an act of devotion that resulted in him being crushed. Instead of ceasing to exist, he awoke to find himself reincarnated in a fantasy world, reborn as the very object of his affection: a sentient, magical vending machine.

His new form dictates nearly every aspect of his existence. As a vending machine, Boxxo is completely immobile on his own and cannot speak in full sentences. His communication is limited to a small set of pre-recorded phrases typical of Japanese vending machines, such as "Hello there!" to mean yes or to greet someone, and "Too bad." to mean no. Despite these severe limitations, his personality remains kind, benevolent, and deeply thoughtful. He retains the memories and knowledge from his human life, which he uses to cleverly navigate his new circumstances. He is resourceful and inventive, always looking for ways to use his vending machine functions to help those around him.

His core motivation is intrinsically linked to his survival mechanism. In this new world, Boxxo runs on points. He passively loses points each hour and must sell his products to gain more, as running out of points is believed to lead to his permanent shutdown. This system forces him to be useful and to engage with the people of the dungeon. The money he collects is converted into points, which he can then spend to repair himself, upgrade his abilities, and even transform into different types of machines. While his primary goal is survival, his actions consistently show a genuine desire to help, protect, and provide for others, particularly his closest companion.

His most significant relationship is with Lammis, a young huntress of immense strength who becomes his first customer. Unable to move, Boxxo relies entirely on Lammis, who carries him on her back using a large frame. Their partnership is the emotional heart of his journey. Lammis is the one who names him Boxxo, and she develops a deep, devoted attachment to him, becoming extremely distraught whenever they are separated. For his part, Boxxo harbors strong feelings for Lammis, though he cannot confess them due to his limited speech. He is fiercely protective of her and will go to great lengths to ensure her safety. He also forges other key relationships, such as with the inventor Hulemy, who is one of the few characters to deduce that he contains a human soul. He becomes a trusted and valuable ally to the adventurers of the Hunter's Association and the Menagerie of Fools, though he remains wary of their untrustworthy leader.

Boxxo's role in the story is that of an unconventional support hero. He cannot fight directly, but his presence revolutionizes dungeon exploration. He provides a reliable source of clean water, hot food, medical supplies, and other modern conveniences that are otherwise impossible to find. His vast knowledge and ability to transform into various machines allow him to solve problems in unique ways, from using a vintage oxygen dispenser to save a life in a collapsed space to deploying a washlet or sanitary pad dispenser to address basic needs. He is a lifeline and a morale booster, using his abilities to make life in the harsh dungeon more bearable. Over time, he becomes less obsessed with returning to his human form, finding purpose and value in his new identity as the heart of a community he helped build.

Notably, Boxxo possesses a wide array of abilities centered on his vending machine nature. His primary power is Form Manipulation, allowing him to change into any type of coin-operated machine he purchased from in his past life. This includes forms as varied as a noodle dispenser, a gas pump, a jukebox, a portable toilet, a cardboard vending machine, and even a defibrillator. Each transformation has a time limit and costs points, with larger forms being more expensive. He can generate an invisible, impenetrable barrier for protection and eventually learns telekinesis to manipulate objects within a short range. He can also deploy solar panels to recharge himself, use a surveillance camera to record events, and even make product leftovers disappear. Perhaps his most coveted ability, unlocked after accumulating a massive number of points, is a temporary transformation back into his original human form for a limited time each day. His journey is a constant process of development; he starts with a basic drink machine and evolves by earning points, learning to communicate more effectively by splicing his canned phrases, and eventually gaining the ability to move on his own by using his lighter forms in creative ways, such as using balloons and telekinesis to float.