
The window between them
Two neighboring rooms, one tiny gap, and a lifelong habit of simply showing up.
Kazuki Yakushi and Mari Tsukami have been inseparable since childhood. High school was supposed to be where they finally found romance somewhere else. Then growing up quietly rewrote the rules.

They share history, trust, routines, private spaces, stupid jokes, and the certainty that the other person will be there tomorrow. At sixteen, that certainty becomes complicated.
Friendship Upgraded is about the awkward territory between genuine lifelong friendship and first love. Not a secret crush finally revealed, but two people realizing that adolescence has changed what their bond can mean.
“Having you as my best friend has been perfect, but I realized that ‘friend’ is no longer enough for me.”— Kazuki, Chapter 28
The same gestures change meaning as Kazuki and Mari do.

Two neighboring rooms, one tiny gap, and a lifelong habit of simply showing up.

The same teasing. The same invitation home. So why does everything suddenly feel different?

When the lights go out, Kazuki becomes Mari’s safe place, and familiar closeness suddenly means something new.

For the first time, the space between their rooms feels much larger than a few steps.
Change is unavoidable. Refusing it is still a choice.
Open, closed, locked. Their shortest path to each other becomes the story’s emotional barometer.
Waiting is safe until someone else decides to act.
Romance does not replace what they were. It adds another layer to it.
Follow Kazuki and Mari from the week before high school to the moment they finally meet halfway.