High school students Yuma Okazaki and Hotaru Mizushina are childhood friends. With their respective boyfriends, Takeda and Fujiwara, their lives couldn't be more perfect. From playing in school to going on group dates, it seems nothing can break their bond. However, during one such group date, Hotaru makes an unexpected move. While Takeda and Fujiwara are distracted, she begins stroking Yuma's thighs. Taken aback by this peculiar action, Yuma awkwardly retreats to the toilets, followed shortly by her aggressor. Now in private, Hotaru forces the innocent Yuma into a locked cubicle and whispers into her ear: You'll be more nervous with a boy; I'll help you practice.

Average high school student Yuuko Konagai tends to be rather shy and socially awkward. Due to this, besides earning rather mediocre grades, she barely has friends inside her class. However, after a monotonous day at school, she returns to her long-awaited haven—home with her cats Maa, Shi, and Ro! With their unique personalities, the three possess bodies similar to those of humans, retaining the ability to speak and communicate. Every day, the adorable bunch awaits their owner's return to shower her with much-needed companionship. Nyanko Days highlights the life of Yuuko and her cats as they brighten up each moment and make new friends in the passing days.

In an attempt to gather information on immortality, scientists from around the world have assembled to study Heaven's Gate—the tomb turned laboratory of the mythical king Gilgamesh. But soon enough, the research is deemed unethical and all planned work comes to a halt. However, a group of terrorists pay this no thought and storm into Heaven's Gate, ultimately causing an explosion that leads to the collapse of the advanced information civilization. Many years after the incident, the siblings Tatsuya and Kiyoko Madoka are on the run from thugs. Yet this seems to be the least of their worries as they find themselves in the midst of a war between two powerful cryptic factions. With both groups claiming to fight for the betterment of society, Tatsuya and Kiyoko will have to find a way to decide who to trust.

High school student Takeru Takemoto works part time as a (motor)bike courier. During one of his deliveries, he saw a mysterious light passing him and fell into a forest. What he had found was a beautiful girl coming out from a glowing cocoon, calling herself Hikari. While Takeru was quite embarrassed because of Hikari's nudity, a strange monster suddenly showed up and immediately attacked the two. Both Takeru and Hikari demonstrated the power of their other selves before Takeru had a clue of what's going on. (Source: ANN)