The Protagonist’s Sister Loves Me, But She’s Definitely a Yandere

The protagonist is busy building his harem again today. Because I live close to him, I’ve been forced to play the role of his childhood friend since we were little. Whatever I do, people compare me to him and end up disappointed. Not that he’s a bad person—he’s the life of the party. That makes me, a guy with no special talents, stand out even more. But one day, I received a love letter. When I opened it, it said: “I like you. I’ll be waiting behind the school building after classes today.” I got more excited than I’d care to admit. —But reality was cruel. The girl waiting there said: “Huh? Who are you?” Apparently, she mixed up the shoe lockers when calling me out. The next day, there was another love letter in my locker. This time, it said: “I know everything about you.”