"Fortune Arterial: Akai Yakusoku" is a 12-episode anime series adapted from the visual novel of the same name. The story centers on Kohei Hasekura, a high school student who transfers to the prestigious Shuchikan Academy, a boarding school on a remote island. Upon arrival, Kohei discovers that the school harbors a secret: it is home to vampires, though they are not the traditional malevolent beings often depicted in folklore. Instead, these vampires coexist peacefully with humans, maintaining a delicate balance.

Kohei quickly befriends Erika Sendo, the cheerful and outgoing vice-president of the student council, and her close friend, the reserved and enigmatic Haruna Yorihime. As Kohei becomes more involved in student council activities, he learns that Erika is a vampire, a fact she initially conceals. The series explores the dynamics of their relationship as Kohei grapples with the implications of Erika's true nature and the responsibilities it entails.

The narrative delves into the history of the vampires at Shuchikan Academy, particularly the Yorihime family, who are central to maintaining the school's traditions and the coexistence between humans and vampires. Haruna, as the head of the Yorihime family, carries the weight of this legacy, which creates tension and conflict as the story progresses. Kohei's presence disrupts the status quo, leading to revelations about the school's past and the true purpose of the vampires' existence.

Themes of trust, loyalty, and the struggle between duty and personal desire are woven throughout the series. Kohei's interactions with other characters, such as the mischievous twins Kanade and Shiro Takatsuki, and the stoic student council president Kiriha Yuh, further complicate the narrative. The series builds toward a climactic resolution involving the school's annual festival, which serves as a pivotal event for both the human and vampire communities.

"Fortune Arterial: Akai Yakusoku" balances supernatural elements with slice-of-life moments, creating a story that is both grounded and fantastical. The characters' relationships and the mysteries surrounding the academy drive the plot, offering a mix of drama, romance, and intrigue. The series concludes with a focus on the bonds formed between Kohei and the vampire community, leaving the door open for further exploration of their world.