This section contains plot details about the novels.
Kazuki Hoshino is the main protagonist of the Hakomari series. A completely ordinary high school student who loves idle chatter with his friends and Umaibôs, a Japanese snack. One day, he is suddenly antagonized by Aya Otonashi — although he has never met her before. She threatens to “break” him.
Kazuki is a small boy with short, brown hair and brown eyes. The illustrations in Volume 6, however, portray him as having black hair and slightly grayer eyes. He is known to have small hands compared to those of his age and is often seen in his school attire or alternatively using a social shirt and a black necktie.
Kazuki loves his normal everyday life, and strives to fight against the boxes that are taking away his ordinary life.
While inside the Game of Idleness, he abandoned his abnormal obsession with the everyday life, describing himself as Maria's "Knight". After killing Kamiuchi inside Kingdom Royale, he started displaying psychotic behavior, going as far as "killing" Shindou Iroha just to save a Maria who was supposedly kidnapped on Daiya's orders. This, however, resulted in Maria losing her trust in Kazuki, meaning that he was left alone.
After being incorporated into Aya's "Flawed Bliss", Kazuki is forced to repeat a blissul day 400,000 (Equal to 1,095 years) times before he is able to escape and destroy Aya and the "Flawed Bliss," thereby freeing Maria from the shadow of her "imperfect sister," Aya. Kazuki was unaware of the repetitions of this day at first, however began to realize that this perfect dream could only be so. As a result of this, he began to forcefully commit suicide, in order to remember the experiences of the previous day. However, after many attempts, he would give up and return to the dream would which he desires. This cycle would repeat until (roughly) the 127,000th repetition, where his psychotic nature that arose during 'The Game of Idleness' meant that he believed his only choice to escape the loop was to kill as many people as required. By the time his killing sprees were completed, and he had removed every human in the world, Kazuki began to lose the human traits that you would associate with a person. This negative aspect carried on throughout the 400,000 iterations that he experienced and into the real world once he had defeated 'O'. This meant that he lost the ability to speak or have any basic emotions.
The story begins when Kazuki is offered a box by 'O'. Kazuki however refuses the box because the only thing that he wishes for is a normal everyday life. Because of Kazuki's disinterest in the box and his will for an everyday life, 'O' becomes interested in Kazuki. 'O' gives boxes to several people around Kazuki, and before Kazuki knows it his everyday is being destroyed in several different ways. 'O' makes it his mission to study Kazuki in these different scenarios until he believes Kazuki will give in and use a box himself. Kazuki later realizes he is the owner of the Empty Box, which is the antithesis of the wish-granting boxes and holds the power to destroy other people's boxes, thus "trampling others' wishes". He describes the Empty Box as a box which wasn't filled with desires. He was given the role of "savior" by Maria's box, the Flawed Bliss, while 'O' is the manifestation of Maria's wish of making other people happy. His disgust for 'O' is caused by a subconscious knowledge of 'O's true nature.