Even Though the Protagonist's Little Sister Loves Me, 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.”