Update: The Horimiya Twitter page has announced that the Horimiya anime adaptation is greenlit for January 10, 2021.
The October 2020 cover for G-Fantasy, a monthly Japanese manga magazine owned by Square Enix, revealed that the Horimiya manga will receive an anime adaptation scheduled for 2021.
CloverWorks is in charge of the animation production. Key staff includes:
Director: Masashi Ishihama (Persona 5: The Animation, Shinsekai yori)
Series composition and script: Takao Yoshioka (Your Lie in April, WORKING!!)
Character Design: Haruko Iizuka (Ensemble Stars!, Inu × Boku SS)
Music: Masaru Yokoyama (Your Lie in April, Chihayafuru)
Haruka Tomatsu will voice as Kyoko Hori while Koki Uchiyama will voice as Miyamura Izumi.
The Horimiya manga, first published in 2012, was written by HERO and illustrated by Daisuke Hagiwara. It originated from a 2007 four-panel webcomic by HERO called Hori-san to Miyamura-kun and received a four-episode OVA adaptation and a spin-off called Hori-san to Miyamura-kun Omake.
Yen Press is publishing the English version of Horimiya and describes the first volume as:
A sweet ‘aww’-inspiring tale of school life begins!!At school, Kyouko Hori is known for being smart, attractive, and popular. On the other hand, her classmate, the boring, gloomy Izumi Miyamura tends to get painted as a ‘loser fanboy.’ But when a liberally pierced and tattooed (not to mention downright gorgeous) Miyamura appears unexpectedly on the doorstep of secretly plain-Jane homebody Hori, these two similarly dissimilar teenagers discover that there are multiple sides to every story…and person!
Source: G-Fantasy Magazine, Official Twitter