One year ago, Sagiri Izumi became step-siblings with Masamune Izumi. But the sudden death of their parents tears their new family apart, resulting in Sagiri becoming a shut-in which cut her off from her brother and society. While caring for what's left of his family, Masamune earns a living as a published light novel author with one small problem: he's never actually met his acclaimed illustrator, Eromanga-sensei, infamous for drawing the most lewd erotica. Through an embarrassing chain of events, he learns that his very own little sister was his partner the whole time! As new characters and challenges appear, Masamune and Sagiri must now face the light novel industry together. Eromanga-Sensei follows the development of their relationship and their struggle to become successful; and as Sagiri slowly grows out of her shell, just how long will she be able to hide her true persona from the rest of the world?

It is a normal day; everyone from deranged military girl Tanya Degurechaff and 16-year-old isekai protagonist Satou Kazuma to expansionist overlord Ainz Ooal Gown and demon sisters Rem and Ram go on with their daily lives. Suddenly, a conspicuous red button begging to be pressed appears before them. Overcome by curiosity, the otherworldly characters push the button, sending them to an unfamiliar world. With no way of escaping, the characters must lead a normal school life and make acquaintances with the others. One thing is certain: the classroom full of fan-favorite eccentric personalities never gets boring!

Shizuku Tsukishima is an energetic 14-year-old girl who enjoys reading and writing poetry in her free time. Glancing at the checkout cards of her books one evening, she notices that her library books are frequently checked out by a boy named Seiji Amasawa. Curiosity strikes Shizuku, and she decides to search for the boy who shares her love for literature. Meeting a peculiar cat on the train, Shizuku follows the animal and is eventually led to a quaint antique shop, where she learns about a cat statuette known as The Baron. Taking an interest in the shop, she surprisingly finds Seiji, and the two quickly befriend one another. Shizuku learns while acquainting herself with Seiji that he has a dream that he would like to fulfill, causing her dismay as she remains uncertain of her future and has yet to recognize her talents. However, as her relationship with Seiji grows, Shizuku becomes determined to work toward a goal. Guided by the whispers of her heart and inspiration from The Baron, she resolves to carve out her own potential and dreams.

Humans have designed countless worlds—each one born from the unique imagination of its creator. Souta Mizushino is a high school student who aspires to be such a creator by writing and illustrating his own light novel. One day, while watching anime for inspiration, he is briefly transported into a fierce fight scene. When he returns to the real world, he realizes something is amiss: the anime's headstrong heroine, Selesia Yupitilia, has somehow returned with him. Before long, other fictional characters appear in the world, carrying the hopes and scars of their home. A princely knight, a magical girl, a ruthless brawler, and many others now crowd the streets of Japan. However, the most mysterious one is a woman in full military regalia, dubbed Gunpuku no Himegimi, who knows far more than she should about the creators' world. Despite this, no one knows her true name or the world she is from. Meanwhile, Souta and Selesia work together with Meteora Österreich, a calm and composed librarian NPC, to uncover the meaning behind these unnatural events. With powerful forces at play, the once clear line between reality and imagination continues to blur, leading to a fateful meeting between creators and those they created.