The Summer Hikaru Died

In a rural mountain village, high school student Yoshiki realizes that his best friend Hikaru is no longer the person he once knew. After a fatal accident, Hikaru's body has been inhabited by a mysterious, otherworldly entity that possesses all of his memories and mannerisms but is clearly something alien. Despite knowing the truth, Yoshiki chooses to continue their relationship, pretending everything is normal. The series explores the eerie, emotionally complex dynamic between them as Yoshiki navigates grief, lingering attachment, and growing feelings for the creature wearing his friend's face, while supernatural phenomena threaten their small community.

The manga is written and illustrated by the pseudonymous Mokumokuren, who first conceived the series while studying for exams and shared character sketches on Twitter/X, where the concept went viral. This online attention led to professional serialization on Kadokawa's web manga platform Young Ace Up beginning August 31, 2021. The pseudonym references a type of Japanese yokai, a one-eyed umbrella spirit, fitting the series' folk horror themes. Mokumokuren maintains a private public profile, with little known about their personal identity.

Critics have praised the series for its unique tone, balancing genuine horror with poignant emotional beats. Mokumokuren's artwork, characterized by heavy cross-hatching and shadow, creates a constant sense of dread and unease. Reviewers from Anime News Network, Polygon, and Otaku USA have called it a love story as much as a horror story, describing it as hauntingly beautiful and a masterclass in melancholic horror. The New York Times and The Guardian have both featured the series, noting its quiet, creeping horror and intelligent meditation on identity.[edit]