From the Start, on a Rainy Night, I Became Shinichi Kudo's Older Brother

I woke up one day as Shinichi Kudo's older brother.

System prompt: [Beginner Mission: Find your shrunken little brother at 2-21 Beika Town]

On a rainy night, I wrapped the shivering little detective in my trench coat. “Call me big brother, and I'll take you in.”

Later, the Black Organization discovered that Shinichi Kudo had an even more terrifying person backing him up:

I altered the forensic reports, snipped the bomb wires, and even made the antidote to APTX 4869… by tapping Gin on the head with a test tube as I mixed it.