Haruki is in his classroom when it happens. His teacher, Ms. Tanaka (age 34), collapses mid-sentence while writing algebra on the blackboard. Within seconds, the school hallways echo with the screams of teenagers — the only ones left conscious.
Shounen ga Otona ni Natta Natsu chapter one introduces Ryuki Kirishima, a young prodigy who, while living alone, becomes inexplicably attracted to an adult film actress named Kiriru. The narrative, heavily influenced by a "Jekyll and Hyde" structure, reveals that Kiriru is actually Reiko, Ryuki’s older sister, who created this persona to act on repressed desires. Read the full analysis at shounen ga otona capitulo 1 cap 1