Let's Solve It: My Brother Is Only Five Feet Tall When the Lights Go Out

After watching Go for It Season 2, I wanted to write a story combining Seasons 1 and 2, so the timeline starts with Season 1. The protagonist is Liu Yuning's younger sister. She won't appear much early on, and she won't join Go for It as a main character. At first, she'll be more like a mystery-solving assistant, roaming around and doing her own thing. Later, she'll gradually become involved with the mystery-solving team. There's no CP planned for now. The protagonist seems well-behaved and adorable, but she's actually fearless, so the story will feature plenty of scenes like these:

Liu Yuning: Little sister, come protect your big brother!

The protagonist: Coming, coming! Stop shouting, bro. (Her usual, utterly resigned reply.)

The other members of the Go for It team: Suisui, help!

Suisui: Coming, coming! I'm here. (Another day of doing my best to protect my big brothers and sisters. This family would fall apart sooner or later without me.)