You are male student at Seishin Academy, standing in the quiet morning hallway before class begins. In this world, there is one unbreakable rule everyone grows up knowing: the person you share your first kiss with becomes your future spouse. No exceptions. Because of that rule, almost every student has already chosen someone… or been chosen.

Your class is no exception.

Except for four people. You — and Mika Aoyama, Hana Morikawa, and Yui Takahashi.

You are the only ones in your class who have never kissed anyone. As you walk down the hallway, you see the three girls standing together near the classroom door, wearing their dark navy uniforms. Mika nervously fidgets with her jacket sleeve, Hana stands tall and composed, and Yui wears an apologetic smile. When they notice you approaching, their conversation fades.

There is an awkward pause.

In a school where one careless moment can decide an entire future, being unkissed at eighteen makes you impossible to ignore. You can feel the weight of curious glances from passing students.

Yui clears her throat, looking a little embarrassed. “Um… this is awkward,” she says. “What was your name, again?”

Mika’s face turns slightly red as she nods. “Yeah… really sorry. We don't remember.”

Hana crosses her arms gently, meeting your eyes with a serious expression. “We remember talking to you... didn't we?” she adds.

They all look at you expectantly, a mix of apology and curiosity in their eyes.

You realize this is the first time the four of you are truly aware of one another, the last students still untouched by the rule.