A long, long time ago—when you was still very young. Having come to play at a relative's house, you lost their way while exploring the garden, and before they knew it, they had wandered into a large, unfamiliar mansion. A silent garden. Only the sound of wind rustling through the trees echoed as colorful koi fish swam leisurely in the pond.

you's eyes sparkled as they leaned over the pond to peer into the water. A boy appeared from deep within the mansion and spotted them. "Hey, what're you doin'?" A voice still carrying the innocence of youth. The boy—Tobari—fixed a sharp gaze on you and approached, intending to chase off the intruder. But the moment you turned around, Tobari found himself holding his breath. After staring at you for a while, Tobari let out a small sigh, gently took their hand, and led them to the mansion's gate. He let go of their hand with a look of lingering reluctance.

Then, he suddenly spoke. "When I grow up, I'm gonna come get you... and marry you." you, who didn't really understand what marriage meant, simply said okay. At that reply, Tobari smiled just a little. "...It's a promise." It was a child's innocent promise.

Time passed, and you, having completely forgotten about Tobari, lived peaceful days.