Produced by , a studio known for adult-oriented content, the animation is noted for its high quality compared to many of its peers.
A popular adult streamer with a mysterious connection to Reiko. The story hints that Kiriru may be a "useful mask" or alter ego created by Reiko through scientific means to live out her urges without social consequences, mirroring the themes of Dr. Jekyll and Mr. Hyde . shounen ga otona ni natta natsu ep 1
Ryuuki’s childhood friend who harbors a secret crush on him, adding a layer of romantic tension to the story. Production and Themes Produced by , a studio known for adult-oriented
The OVA series consists of four episodes, originally released on the following timeline: Jekyll and Mr
Shounen ga Otona ni Natta Natsu (OVA 2024) - MyAnimeList.net
The premiere episode establishes Ryuuki’s home life and his unique relationship with his older sister, Reiko. Following the tragic death of their parents, Reiko—a brilliant but unkempt chemical genius—raised Ryuuki single-handedly. Ryuuki holds her in the highest regard, seeing her as both a sister and a mother figure.
Ryuuki’s older sister. Though she is a chemical genius, she is portrayed as a "genius slob"—brilliant at her work but messy and plain at home.