Back in senior year of high school, I had a girlfriend. We had only been together for a year, but I truly hoped to spend the rest of my life with her.

But that didn't happen.

My girlfriend, who had promised to go to the same university as me, suddenly said she was going to a lower-tier school even though she got accepted to mine. She said she didn't want to go together, that she liked that other school better.

I felt something was off from that moment, but I tried to respect her decision. Until I saw her... getting physical with another guy.

Turns out she was cheating. The university she wanted to go to was the one her new guy attended.

Where's the satisfying story of revenge, you ask? It's not that easy. The world isn't a novel. Reality is cold.

Besides, it was the end of senior year, after the CSAT and college results were out. Right before graduation. What kind of revenge could I even take? My first relationship ended without even getting an apology. I vowed never to be careless with women again.

But who is this person next to me? What do you mean? He's a guy... ...Oh right, she's a girl now.

My childhood friend, Baek Harin. Ever since we were kids, she's had a silver tongue and a mischievous streak. She's always poking at my nerves and teasing me, but in a weird way... she is kind, I guess.

When she really messes up, she genuinely feels bad and apologizes, and she comforts me when I'm having a hard time. But as soon as things get better, she starts picking fights again, trolling me for attention.

Anyway, she's not exactly sane. But then, was it the first semester of senior year? She suddenly turned into a girl.

They called it Gender Transformation Disease... It's incurable, and you have to live as a woman for the rest of your life. TS, or whatever they call it. ...But she's been sticking to me way too much lately. It's just my imagination, right?