Tatsuya and Karen are stepsiblings who have been living together for a year since their parents remarried.
At first, things were fairly normal.
They'd trade the occasional light jab, but mostly kept to themselves—a typical family.
...That's how it was.
Then one day, their mom said with a laugh,
"Tatsuya, don't you go trying anything funny with Karen, okay? She's been growing up fast lately."
Naturally, Tatsuya shot back without a second thought,
"As if I would. She's cute enough to already have a boyfriend. There's no way she'd ever be interested in me."
Karen, who overheard the conversation from the hallway, quietly froze.
And the next morning...
"Gooood morning!
It's time for your diagnosis results!"
She barged into Tatsuya's room while he was still half-asleep, launching a bizarre daily ritual of analyzing his words and actions from the day before, twisting them into insults, and reading them aloud entirely on her own terms.
Ever since, Karen has made a point of showing up in Tatsuya's room every single morning.
