Ghosts

Ghosts are referred to be supernaturals who were previously alive and may have attended Kamome Gakuen as a student in the past. However, they only exist due to their lingering attachment or regrets before dying.


 * According to his role as No. 7 of the School Wonders, Hanako's regret is not explicitly mentioned. In Chapter 3, he states that God gave him the chance to absolve his sins in his past life by granting wishes.
 * Tsukasa's regret or purpose has not been revealed in the manga, but he still holds a tangible existence as a ghost.
 * Mitsuba's initial regret was that he wanted to take a certain picture, uncertainly. However, his past reveals that he had been outcasted by other students his age due to his cocky personality and later, his lack of presence. Although he had made a deal with Tsukasa (which led to the rumor of the ghost residing at the lockers), his regrets were fulfilled when he took a picture of Kou, whom he considered his first friend.

Abilities
Physically, ghostly characters are often translucent or see-through, unable to be seen by humans aside from the supernatural, those close to the Far Shore, or exorcists, and can possess powers depending on their role (eg. Hanako and Mitsuba being part of the School Wonders). From Chapter 11 of the spin-off, Tsuchigomori states that ghosts and supernatural alike can get contagious colds with expected symptoms--with the tell-tale signs of a bedridden Hanako going through a drowsy fever. Evidently, these sicknesses don't affect humans. The only way they can directly affect normal humans is by possessing them. This causes their host to have matching eyes and the same personality as them.
 * It is speculated that they are also bounded to the school permanently as seen by Hanako's hesitance in leaving the school gates or being unable to go to the summer festival with Kou and Nene.
 * They can live for many years without changing their age or appearance. Judging by the timeline from when Hanako was a human, he is presumed to have lived more than 50 years in Kamome Gakuen before Nene's visit.
 * Ghosts lose many capabilities from when they were human, so they no longer have the need to sleep or eat. Hanako bluntly states he doesn't have to sleep, suggesting that he can but at certain occasions.
 * Like supernaturals, they are able to exist on the Near Shore through rumors, but they must fit the criteria of them. Kou explains that ghosts also have a soul core inside them. By finding that core, Teru can successfully eliminate a ghost through electric shocks as seen in the Young Exorcist arc.
 * They are able to eat the parts or organs of other supernaturals. In the Hell of Mirrors arc, Tsukasa had forced Mitsuba to swallow the former No.3's heart in order to become No. 3 himself. Because of this, Mitsuba's hand had became a deformed bird's talon along with dark feathers sprouting in his hair. In Chapter 10, there is an unusual agglomeration of creatures behind Hanako, to which Teru states he was a volatile ghost who would harm others at the slightest provocation.
 * They do not have reflections in either mirrors or photographs (eg. Hanako's reflection not appearing in the mirrors aside from Nene's and Kou's appearances). When Nene and Kou attempted to take a picture together with Hanako in the spin-off, Hanako's appearance only came off as a silhouette of shrieking ghosts.

Volume 0
Although Volume 0 is not part of the canonical manga's plot, there were several characteristics that Hanako explains.
 * He cannot physically eat food, but he can acquire the food's taste and texture. He left Nene's bento box untouched despite already eating it. However, this trait may have been removed from the actual manga considering Tsukasa's ability to eat the available desserts in the tea party.
 * The Fox's Eye was referenced in some official artworks, and this was considered another way to see supernaturals like the Mokke. By painting three fingernails and making a gesture to resemble an eye (alternatively the gesture used to make a rabbit silhouette), one can see supernaturals by looking through the lens they made.
 * Whatever a ghost holds doesn't have the ability to affect living beings other than passing through them. Hanako exemplifies this by playfully putting his knife through Nene's body and going through her. The same can be said for Mitsuba's attempt at trying to give back someone's handkerchief only to find they cannot feel nor hear him.