Mitsuba is cocky, foul-mouthed, and overly confident, particularly when it comes to his appearance, often bragging about how cute he is. He has a tendency to give people rude nicknames and is not afraid to insult others. Despite his abrasive personality, he is also quite calculating—he knows how to manipulate people, acting nice when it benefits him or when he wants to gain their trust. However, beneath his bravado, Mitsuba is easily brought to tears, especially when placed in threatening situations.

His difficult childhood shaped his personality. In elementary school, his natural demeanor made him a target for bullying, leading him to create a gentler, more agreeable persona in middle school in an attempt to fit in. During this time, Mitsuba presented himself as kind, considerate, and friendly in hopes of making friends. However, this effort ultimately failed, as he was overlooked by his peers and ended up forgotten, leaving him without any real friendships.

Despite his rude and outspoken nature, Mitsuba has a softer, more vulnerable side. He becomes noticeably melancholic when discussing his past, and while he gets lonely easily, he struggles to express his emotions honestly, choosing instead to mask his feelings with harsh words. However, there are moments where he can genuinely show happiness and kindness, especially around those he grows comfortable with.

Mitsuba has a strong passion for photography, to the point of obsession, according to Kou. As a member of Kamome Academy’s Photography Club, he had even won several awards, demonstrating his talent and dedication to capturing moments through his camera.

Mitsuba has an androgynous appearance, with many of his classmates commenting on his girlish features. He tends to wear mostly pink outfits, further emphasizing his delicate look. He is a slender and relatively tall middle school-aged ghost with soft pink hair and matching pink eyes. A mole under his left eye adds to his distinctive features. His medium-length hair has bangs that cover his right eye, while the back of his hair is usually tied into a small ponytail, held up by bobby pins. He also wears a teal helix piercing on his left ear.

The Original Mitsuba wears a yellow scarf with light brown stripes and a long-sleeved pink sweater over his Kamome Academy Middle School uniform. His right sleeve always covers his hand, giving him a slightly reserved appearance. After Tsukasa recreated him in Volume 6, the Current Mitsuba began wearing a red scarf with tassels on both ends, marking his transformation.

A scar on the back of his neck is presumably a remnant of the accident that caused his death. Additionally, burn marks on one side of his scarf suggest they may have resulted from the same incident.

In his earlier years, Mitsuba was bullied for his cocky attitude, feminine appearance, and foul-mouthed personality. As a result, he later altered his behavior, becoming more passive, friendlier, and unintentionally dull when he entered Kamome Academy. When he first met Minamoto Kou, he had softer eyes and a gentle smile, with his short hair tied into a ponytail and his bangs neatly parted to the side.

As the new representative of School Mystery No.3, Mitsuba’s appearance becomes significantly altered. He wears a tattered black jacket adorned with eye-like patterns over his regular clothing. His hair is speckled with black feathers, a sign of his supernatural transformation. His red sneakers are replaced with black boots that have shackles attached to his right shoe, further emphasizing his ghostly nature. Additionally, his remaining arm is replaced with a bird-like talon, reinforcing his connection to his newly acquired supernatural form.

His red scarf transforms, now featuring golden trinkets and a lock attached to it. The scarf also extends into bony exoskeleton-like appendages, which Mitsuba can manipulate and use in combat.

Throughout the series, Mitsuba is repeatedly noted for his good looks, a fact he himself acknowledges. However, the former 3rd School Mystery once remarked that he is only slightly above average in terms of appearance, contradicting Mitsuba’s own high opinion of his looks.

During his early school years, Mitsuba was frequently bullied due to his cocky attitude and androgynous appearance. Hoping to avoid further mistreatment, he deliberately changed his personality upon entering junior high, adopting a more passive and caring demeanor in an attempt to make friends. However, his efforts largely failed, as he was dismissed as a boring background character, leaving him feeling isolated.

In the following years, Mitsuba reverted to his original personality, yet accounts from his classmates, former teacher, and the photography club indicated that he rarely interacted with others. When Nene and Kou visited Mitsuba’s house after tending to his grave, his mother revealed that his passion for photography was inspired by his father, who taught him how to use a camera. Although Mitsuba won awards for his photographs, he primarily focused on nature and animals rather than people. When his mother suggested that he take a picture of her, Mitsuba arrogantly dismissed her fashion sense, teasing her to put on makeup first. Despite his conceited and blunt personality, he still held genuine affection for his loved ones, though he struggled to express it openly.

One of Mitsuba’s hidden acts of kindness was his plan to surprise his mother on her birthday by cooking her curry, a gesture that deeply touched her despite his constant complaints about her doting nature. Tragically, while running to buy missing potatoes on a winter day, Mitsuba was involved in a fatal accident on the road. His untimely death marked the last day his mother ever saw him, leaving a profound loss that would linger in her heart.

As a low-level ghost, Mitsuba was partially visible to the human eye under specific conditions. When he grabbed a person’s hand and asked if they knew who he was, he would briefly appear, albeit in a distorted form. Under normal circumstances, he was invisible to most humans, except for those with supernatural affiliations, such as Minamoto Kou.

After Tsukasa forcibly altered his rumor, Mitsuba lost all traces of his humanity and was transformed into the monstrous entity known as the Bent-Neck Boy at the School Entrance. His body became an unsettling amalgamation of eyes and camera parts, loosely held together by bandages, with a large, exposed crevice in his chest. In this form, he no longer shed tears; instead, a dark, inky substance flowed from his eyes and mouth.

Mitsuba’s abilities in this form included using his bandages to attack and entangle victims. However, he was completely unresponsive to others, seemingly unable to remember Kou or their past connection. Yako later reflected on her own experience of having her rumor altered, describing it as if she were herself, yet also not herself. This suggests that Mitsuba may have still recognized his surroundings but was unable to react or respond.

After consuming the heart of the former School Mystery No. 3, Mitsuba was reborn as the new representative of the 3rd School Mystery. He gained control over the Hell of Mirrors boundary, allowing him to manipulate the space at will. This was demonstrated when he effortlessly expelled Nene and her companions from the boundary.

As the new School Mystery No. 3, Mitsuba possesses the ability to manifest within the mirrors of Kamome Academy. He can access past reflections captured in those mirrors, using them to gather information about his past and the world around him.

His red scarf, now resembling an exoskeleton, functions as an extension of his body, acting as extra limbs that he can control freely. However, when overwhelmed by distress or fear, the scarf moves involuntarily and attacks anyone he perceives as a threat, making it both a weapon and a reflection of his unstable emotions.

Mitsuba Sousuke is one of the most tragic and emotionally compelling characters in Toilet-Bound Hanako-kun. His journey from an ordinary student to a forgotten ghost, then a twisted School Mystery, reflects themes of loss, identity, and the struggle to hold onto one’s humanity.

His bond with Minamoto Kou serves as one of the series’ most heartfelt relationships, showing that even in the darkest circumstances, friendship can persist. However, his fate remains uncertain, as he continues to battle against Tsukasa’s control and his own fragmented existence.

Mitsuba’s story highlights the consequences of supernatural interference and raises deep questions about selfhood and fate, making him one of the most unforgettable figures in the series.