Chitose Hitotose is the central protagonist of his narrative, a high school student whose life is defined by a profound sense of loss that slowly transforms into an embrace of an unconventional family. He becomes an orphan after his parents perish in a marine accident during his childhood. Following this tragedy, he resides in an orphanage where he forms deep, sibling-like bonds with two other children, Minazuki and Hazuki, who come to be regarded as his adopted sisters. Upon leaving the orphanage, Chitose moves back into his deceased parents' home, living alone and struggling to adapt.

As a result of his traumatic past, Chitose initially presents a proud, guarded, and distant exterior. He becomes a troubled student with declining grades and a reputation for fighting, isolating himself from others. Despite this tough facade, he harbors a deep well of affection and concern for those he allows to get close to him, demonstrating a strong protective instinct when people he cares about are in trouble. He is generally oblivious to the romantic feelings others have for him, such as those from his class president Fumitsuki Nanakorobi, which is a recurring aspect of his interactions.

The primary motivation driving Chitose's life is his need to cope with his parents' death and find a place where he belongs. His journey begins when five of his female teachers, concerned by his failing grades and solitary existence, take drastic action. They independently decide to move into his house, declaring themselves his new "mothers" to guide and care for him. Chitose is initially resistant to this forced cohabitation, but over time, his role in the story becomes that of a reluctant but ultimately accepting son. He gradually learns to rely on his unconventional family, navigating the chaos and comedic mishaps they bring into his life.

His key relationships form the core of the story. The most significant is the collective bond with his five teachers—his homeroom teacher, the science teacher, the school nurse, the art teacher, and the physical education coach—who each take on a maternal role in their own eccentric way. He also shares a complex, rivalrous relationship with a transfer student named Nagatsuki Kuron, whose background of loss and combat skills mirror his own, creating a deep, if confrontational, understanding between them. His bonds with his sisters from the orphanage, Minazuki and Hazuki, remain a steadfast and loving part of his life, representing his first experience of found family. A notable romantic development occurs with his homeroom teacher, Mutsuki, with whom he eventually shares a mutual kiss, acknowledging feelings that transcend their original student-teacher and faux mother-son dynamic.

Chitose undergoes significant development throughout the series. He transitions from a solitary delinquent prone to fighting to a more well-adjusted individual who accepts and appreciates the chaotic love of his five mothers. His emotional walls slowly erode, allowing his genuine affection for his family to surface. By the conclusion of the main story, his journey comes full circle when his five mothers decide that what he now needs are not mothers but wives, leading to a group marriage ceremony that solidifies his place within his cherished, unconventional family.

Among his notable abilities, Chitose is a highly skilled fighter. He frequently demonstrates this prowess by easily defeating bullies who taunt him for being an orphan and holding his own in physical confrontations with his rival, Nagatsuki. He also displays a remarkable resilience, often appearing unharmed after enduring significant physical abuse and comedic accidents at the hands (or experiments) of his well-meaning but over-the-top mothers.