Welcome to Demon School, Iruma-kun season 3 has received a new key visual, as well as an October 8 release date. The production is overseen by Bandai Namco Pictures, and the new visual is available here:

The announcement was previously teased on the official Twitter account, which coded the date and time of the announcement in the Demon World language from the story. The new season will Focus on the Harvest Festival.
— アニメ『魔入りました!入間くん』【NEP公式】 (@nep_irumakun) August 14, 2022
Osamu Nishi writes the original Welcome to Demon School, Iruma-kun (Mairimashita! Iruma-kun) manga, which has been serialized in Weekly Shonen Champion since March 2017. Season 1 of the anime adaptation started airing in Fall 2019 and ran for a total of 23 episodes until March 2020. Season 2 ran for a total of 21 episodes starting in April and ending in September 2021, after which Season 3 was announced.
Crunchyroll streams the anime, and they describe the story:
Suzuki Iruma, human, 14, one day finds himself taken against his will into the world of demons. To add to his predicament, his doting owner and self-appointed “Grandpa” is the chair-demon at his new school. In order to survive, Iruma must deal with a haughty student who challenges him to a duel, a girl with adjustment issues, and so many more scary beings! Can this ultimate pacifist dodge the slings and arrows that are flung his way? As he struggles frantically, Iruma’s innate kindness begins to win over enemies.