Kimi no Tonari de Nemuritai

A girl named Kazuiko caught a cold from a man she encountered while traveling to her university entrance exam. On the exam day, she developed a fever and cursed the man, whose only known detail was that he was also taking the same exam and had the ID number #400. Later, while cleaning her apartment and dusting her sheets on the balcony, she spots a man who seems familiar. She wonders who he might be.