At school, Eriko Ichimura is a nobody. She looks plain, and her classmates overlook her existence until they need to dump their responsibilities on her. On Twitter, however, she is "Lovesick Ellie," a girl with a vivid imagination who writes posts inspired by her fantasies. Akira Oomi, the object of her fantasies, is the most attractive boy in her school, and everything about him seems to be perfect.

Eriko's fantasies take a hit when she accidentally eavesdrops on a conversation between Akira and their homeroom teacher. His true nature is laid bare—he is, in fact, a foul-mouthed and insensitive snob. But when she clumsily forgets her phone at the scene, Akira himself approaches her to return it; however, he has already skimmed through her embarrassing Twitter posts. What Eriko does not expect is him offering to help her realize her fantasies—but only if she stays silent regarding his character.

Trouble seems to follow Eriko wherever she goes, and her luck is absolutely the worst... or is it?

Koiwazurai no Ellie was nominated for the 42nd Kodansha Manga Award in the Shoujo category in 2018.

A drama CD adaptation of Koiwazurai no Ellie was released on May 13, 2020, and sold separately from the manga. Its cast comprised of Ari Ozawa as Eriko Ichimura; Nobuhiko Okamoto as Akira Oumi; Saori Oonishi as Sara Misaki; Kazuyuki Okitsu as Kiyoshi Shiota; and Yuusuke Shirai as Aoba.

Koiwazurai no Ellie was published digitally in English as Lovesick Ellie by Kodansha USA from November 28, 2017, to February 16, 2021.