On Christmas Eve, Hiro Hirono runs into Miyako Miyamura, a frivolous girl who "borrows" his bicycle in order to chase down a purse thief. After Hiro finds his bicycle wrecked and Miyako unconscious, the two unexpectedly spend their Christmas Eve together, and when they discover they go to the same high school, their accidental relationship develops even further. This sparks the jealousy of Hiro's childhood friend Kei Shindou, whose pure approach to life catches the eye of Kyosuke Tsutsumi, a womanizing photographer searching for the perfect shot. Elsewhere, Renji Asou, a boy who dreams of being a girl's knight in shining armor, has a chance encounter with Kei's twin sister—the overly shy Chihiro Shindou, who spends her time reading alone—at an abandoned train station. The two quickly become friends and eventually decide to write a novel together. However, when Renji discovers Chihiro's secret, a disability that causes her to have an eternally ephemeral memory, his childish ideals will be put to the test. Guided by two mysterious adults, these youths' relationships intertwine in a heart-rending tale of love, rejection, acceptance, and memories.

In a story set years in the past, Himura Yuu is a studious and diligent young man intent solely on maintaining his top academic position at Otowa Academy. One day, he meets a mysterious girl named Amamiya Yuuko, who, to his surprise, recognizes him. Memories of a distant childhood, memories rather left forgotten... meeting Yuuko again will force Yuu to confront the regrets and sorrows of their collective pasts and presents. In the present, Kuze Shuuichi may seem like a womanizer, but upon closer inspection, is a man who would rather be left alone. Hayama Mizuki, however, is not the type of girl who would let him be, especially after hearing the beautiful sounds of his violin performance. As Mizuki attempts to become closer to him, Kuze attempts to push her away—the tale of their budding relationship is darkened with undertones of an imminent tragedy.

The Armed Detective Agency is still on the run from the Hunting Dogs, but not all hope is lost. Detective Ranpo Edogawa has a plan to prove the Agency's innocence and save the world from chaos: to find and capture Kamui—the leader of the terrorist organization Decay of the Angel. In order to determine Kamui's whereabouts, Ranpo and his colleague Atsushi Nakajima must convince Genichirou Fukuchi, the renowned captain of the Hunting Dogs, for amnesty. Although Fukuchi was tasked with arresting the members of the Agency, his past with the Agency's president, Yukichi Fukuzawa, may be the key to earning his trust. But unbeknownst to them, Fukuchi might not be as honorable as he proclaims.

The protagonist Wu Liuqi originally lived a carefree life on Xiaoji Island, but his identity became a mystery due to amnesia. As outsiders landed on the island and recognized Wu Liuqi, various conspiracies began to cover Xiaoji Island. So Wu Liuqi decided to return to Xuanwu Kingdom to meet his destiny in order to protect his partners and their homeland.