Ren Sato lives an ordinary high-school life – spending his days playing computer games, reading manga and light novels, and occasionally doing sports either to clear his mind or because his little sister, middle-schooler Yumeko Sato, forces him to. But what he enjoys most in the evenings is watching the live streams of streamer HikariAi. Then his ordinary high-school life is thrown into chaos by his classmate and class president Airi Fujimoto – someone he can't help but feel he has known from somewhere beyond school. What will come to light between them and what dangers does it bring with?