I was reincarnated as a girl, and my high school homeroom teacher turned out to be my childhood friend who I was dating in my previous life!?

"Kayoko, I... I love you! Will you go out with me!" The day before summer break in my first year of middle school. I finally confessed to my childhood friend Kayoko behind the school building where no one could see us. But Kayoko's response was―― "...I'm so happy. I love you too, Ryuji!" Saying that, Kayoko hugged me tightly. Yesssssss!!!! All right!!!! "In exchange, stay by my side for the rest of your life, okay?" "Yeah, of course." I hugged her back as if making a vow. Today is the best day of my life―― ――But this happiness didn't last long. One day, as Kayoko and I were crossing at a crosswalk, we were hit by a truck whose driver had fallen asleep. "No, nooooo, Ryuji!!!" I can't breathe... My vision blurs... Am I going to die...? That's when it happened. A brilliant light enveloped my entire body. Ah, how wonderful this feels... Is this what it means to be welcomed by heaven...? "Wahhhhh, wahhhhh, wahhhhhh" ...Huh? A baby crying? "Congratulations. You have a healthy baby girl." "Ah, how cute...! Hehe, she's so tiny, isn't she?" ...!? I'm being held by an unfamiliar beautiful woman. Who...?! "Wahhhhh, waahhhhh" "Hehe, she's so energetic for just being born." Oh, I'm the one making that crying sound... ...It seems I've undergone what's become popular lately――reincarnation. ――And as a girl, no less. ――And fifteen years have passed. "...Sigh" My second life as Hinamoto Mami. I'm now sitting in the classroom after the high school entrance ceremony, waiting for my homeroom teacher to arrive. While I feel nostalgic thinking that the high school life I couldn't experience in my previous life is starting today, I can't help but think about Kayoko. "Congratulations on your entrance, everyone." "――!!" That's when it happened. A woman in a suit, apparently my homeroom teacher, briskly entered the classroom. The moment I saw her face, I was speechless―― "I'm Numata Kayoko, and I'll be your homeroom teacher starting today." It was Kayoko herself, grown into an adult woman.