The Secret After-School Sex Diary

The Secret After-School Sex Diary is an anthology of short ecchi comedy strips originally posted on Twitter/X and later compiled into collected volumes. Rather than following one continuous plot, each chapter delivers a self-contained gag that drops readers into a perfectly ordinary moment — a summer trip to the sea so merciless it was retitled "The Human World Is Hell," dinner at a tonkatsu restaurant, a private tutoring session, the walk home after class — and lets it escalate into flustered misunderstandings, cheeky innuendo, and punchlines about the secret desires everyone tries to hide. The cast rotates from story to story: Moriko, a succubus doing her best to navigate everyday life; Okayama-san, the pierced girl quietly guarding an unexpected secret; the eventful after-school hours of Serizawa-san; genius planner Kyouko; the self-proclaimed "Valentine Hunter" Matsuzaki; and a stoic everyman who answers only "so-so" no matter what catastrophe befalls him. Elsewhere, a battle-manga couple reveals what their mornings really look like, a high school tutor shows up dressed a little too lightly, a public morals president meets his match, and the author himself appears in meta-strips chronicling his late-night battles with the platform's sensitive-content filters. Light, cheeky, and good-natured throughout, the series mines its comedy from adolescent awkwardness and the gap between how people present themselves and what they are secretly thinking — a quick, punchy collection for fans of slice-of-life gag manga with a risqué edge.