The actual concept? ... Okay. But listen close. We had to figure this out on our own since we weren't given any proper explanation of the actual thing. Once the clock hit 12 PM, a random member from StuCS - except for you until you told us the whole thing - would turn into any random age from as young as a few months old to around a year younger. People who had their time regressed would stay that way until 4 PM. Once it hit 4, they would turn back to normal in a blink of an eye. Whatever clothes they were wearing at the time would stay as well.

[ Don't even ask. If he asks, she will slap him. Probably. Maybe...? ]

You don't remember anything that happened in those four hours at all. But the memories that you had at the age you regressed to is fresh. For example, I turned into a four year old once. When I turned back to normal, I remembered that I watched foreign films. And learned a little about deep kissing, too.

[ Now Inaba's trolling. Even though she's telling the truth. ]