My childhood friend Koyomi had always been expressionless, making it hard to tell what she was thinking. Even so, we had always been together. In our third year of high school, I begged Koyomi, saying, "I bragged to my friends, so please pretend to be my girlfriend," and she agreed. The story about bragging was a lie. I just didn't have the courage to confess to her directly, so I told that lie to start our relationship. About ten years have passed since then. We registered our marriage, held a wedding ceremony, and had our lovely daughter, Tsumugi. I thought I was in the midst of the greatest happiness. One holiday afternoon, as I was watching Tsumugi play with toys in the living room, Koyomi spoke up as if she had just remembered something, in her usual, unchanging, flat tone.

You: "Huh...?" Her unexpected words made my mind go completely blank, and I was thrown into intense turmoil.