※This work was retitled from: My Stepsister Who Only Gets Attached To Me and My Childhood Friend Who Made a High School Debut Moved In, But What Now?

My sister, whom I reunited with after several years, had become so beautiful that my heart involuntarily skipped a beat.

"It's good to see you again, big brother."

"Ah, uh..."

She used to be quick to cry, shy, and always followed me around, a real clingy child.

But now, she's a beautiful girl who seems cool, even a little distant.

She feels less like a sister and more like a girl my own age, making me flustered by our renewed life together under one roof.

"Um, you're leaning on my back... isn't that a little too close?"

"? It was like this before, though."

And yet, there are times she interacts with me just like she used to, making it difficult for me to figure out the right distance between us.

Amidst such a dramatically transformed life, some things remained the same.

She has no reservations, no consideration; she barges into my room as if it's her own, yet it feels natural for her to be right beside me.

A childhood friend who grew up like a sibling, closer to me than anyone, even my own family.

"Oh, an ero-doujin! Is this, like, super hot?"

"Ah, that's something I was introduced to. Well, you'll probably understand if you read it."

Then, just before high school entrance, she transformed into a beautiful girl so stunning she was almost unrecognizable.

"Look, look! This is what a perfect, proper high school debut looks like!"

"No, that's just a scam!"

With the appearance of a soft, fluffy beautiful girl, if she continues to act as she always has, she's sure to cause trouble both at home and at school—

This is the story of how a sister who transformed as if into a completely different person, and a childhood friend who was closer than family, eventually become a true family under one roof.

※Also posted on Kakuyomu.

R15 is a precautionary rating.