Lily Baker, a young English girl, decides to go to an arcade on Valentine's Day. She is determined to win a stuffed animal from a claw machine; but even after attempting it for hours, she is unable to get her hands on the prize. Just as she is about to give up, arcade employee Renji Kusakabe steps in and wins the prize for her as a present to celebrate the special day. Due to her cultural background, however, Lily mistakes his action as a declaration of love! With Lily returning to the same arcade in the hopes of seeing Renji again, the two begin exchanging a notebook to learn more about each other and their respective cultures. This marks the start of a friendship filled with gaming, but that is not enough for Lily, as she swears to make Renji fall in love with her!

Surrounded by four armies of dark beasts, five humanoid races strive to push the known boundaries of the world. Unfortunately, the 13 heroes dispatched to the southern region are easily wiped out by Clevatess, one of the Lords of Dark Beasts. Determined to get revenge against humanity, Clevatess bursts into the capital of the Kingdom of Hiden, leaving a trail of death and destruction behind him. Although the situation looks desperate, humanity still has a chance to appease Clevatess' anger. Alicia Glenfall, one of the 13 heroes, is revived by Clevatess to help him raise a newborn infant, Luna, whose choices shall shape the fate of the human world. Although reluctant to help the dark beast at first, Alicia understands that Luna is the only thing that stands between humanity and complete annihilation. Hiding himself by taking on a human form, Clevatess sets out in search for a wet nurse with Alicia and Luna. With Clevatess unwilling to reveal his identity, it falls on Alicia to slay all enemies that stand in their way. Meanwhile, the neighboring countries prepare to advance on the weakened Hiden, aiming to control the only forge capable of producing the heroes' weapons.

High school first year Yuu Yuutani has always been a good girl, following the rules, helping out around her house, and generally going through life unnoticed. From afar, she reveres her upperclassman and the school's Public Decency Officer, Atori Mizutori, and desperately wants her attention. When she realizes that the best way to get Atori to notice her is to be a delinquent, she begins to dress differently: she dyes parts of her hair a bright red, wears clips on her ears to resemble piercings, and attaches jumbo erasers to her shoes to give them thicker soles. Despite Yuu's best efforts and even with the advice of her "natural born delinquent" friend Suzu Suzukaze, all of her plans to be a bad girl go awry. Still, Yuu manages to befriend Atori and pledges to spend as much time as possible together, not knowing there are others vying for Atori's attention. In the process, Yuu has also gained the attention of the school's self-proclaimed idol, Rura Ruriha, filling her once-invisible life with more attention than she may be able to handle.

In Doumori, an imbalance of spiritual forces threatens to plunge the small city into complete chaos. Thankfully, for the students of Doumori Elementary School, new teacher and exorcist Meisuke "Nube" Nueno is determined to prevent the malignant spirits—known as youkai—from accomplishing their evil deeds. The first student who catches Nube's attention is transfer student Hiroshi Tateno, who displays inexplicable outbursts of anger, often lashing out at his classmates. When they find out that Hiroshi is possessed by a youkai, Nube manages to free his student thanks to the demonic power sealed in his left hand. However, a youkai hiding behind the appearance of doctor Kyousuke Tamano bursts onto the scene and quickly abducts Hiroshi. Helped by his student Kyouko Inaba and his expertise in the occult, Nube quickly uncovers Kyousuke's sinister plans. Rushing to Hiroshi's rescue, Nube will show once more that he will stop at nothing to protect his beloved students against all supernatural threats.