The OVA series consists of four episodes, originally released on the following timeline:
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. shounen ga otona ni natta natsu ep 1
Produced by , a studio known for adult-oriented content, the animation is noted for its high quality compared to many of its peers. The OVA series consists of four episodes, originally