Ryouhei Arisu is a high school student with no ambitions and just wants to escape from what he feels is a meaningless reality. One night when he is with his two friends Daikichi Karube and Chouta Segawa, they see an abnormally large firework shoot into the sky, an event which signals a permanent change in their lives. Blinded by the incredibly bright explosion, the three find themselves transported to what is known as the Borderland. The only inhabitants of this world are participants of a deadly game where specific tasks must be accomplished if they wish to survive. As the three begin playing to determine how they can get back home, Ryouhei finds himself feeling alive for the very first time in his life.

Ever since he published a picture that sparked a wave of online harassment, freelance photographer Kouya Madoka has lost everything: his wife Saeko Yukihira, his confidence, and his courage to photograph people. However, years later, a job offer introduces him to the exhilarating world of Formula 4 (F4). A single fierce battle between the amateur drivers in the junior category of open-wheel car racing becomes enough to make Madoka unable to put his camera down. When Komaki Motors' Haruka Asahina bursts into tears on the track, Madoka manages to capture this vulnerable moment. This photo eventually leads Madoka to an impulsive decision: he will help sponsor both the Komaki team and Haruka himself. But the unreasonable costs of the sport quickly cause Madoka to reassess his ambitions, and he seeks different ways to support the severely underfunded F4 team. Despite the uphill battle, Madoka's determination for Haruka to succeed may be the trigger that can propel the young driver straight to the top.

After the final battle against Gaito, Sara had given her life to remain with him. The sea world is now at peace, but only with six mermaid princesses. While Caren, Noel, and Coco have returned to their kingdoms, it should be time for Lucia, Hanon, and Rina to do the same. After all, Mitsuki Tarou is leaving for Germany, and Doumoto Kaito is heading to Hawaii. Lucia is devestated, and when things couldn't get any worse, Kaito is lost at sea! Worst of all, a strange angel named Michel has appeared, wanting the mermaids to join him. But on the lighter side, Sara's spirit tells Lucia of Sara's successor, a young mermaid named Seira. The mermaids are in for another adventure!

High schooler Aoi Mashiro moved from home six months ago, but her recent breakup has made her want to return to tell off her ex-boyfriend. In need of money for a train ticket, she steals two hanging scrolls from her grandfather's attic and takes them to be appraised at an antique shop in the heart of Kyoto's Teramachi Sanjou shopping district. Little does she know that a fateful encounter awaits her during this visit. Upon entering the shop, Aoi is greeted by Kiyotaka Yagashira, the owner's grandson and a graduate student at Kyoto University. Nicknamed Holmes for a pun involving his surname, as well as for his incredible deductive skills, Kiyotaka inspects the scrolls that Aoi brought with her. Based on the items she selected to sell, Kiyotaka senses that Aoi possesses great intuition not unlike his own. Seeing her potential and sympathizing with her story, Kiyotaka offers Aoi a part-time job so she can earn the required money herself. Aoi and Kiyotaka begin working together soon after—not only within the antique shop, but also around town whenever the locals ask for help with their various problems. With Kiyotaka's deduction and Aoi's intuition, no case is too tough for this modern-day Holmes and Watson duo!