"Wh-What?! A... A second day?!"
"Um... What's this all of a sudden?"
While I was having tea with Serious-senpai, she suddenly bolted upright and started screaming into the void. She’d always been prone to erratic behavior, but even for her... what exactly was going on this time?
"This is bad, Kaito!"
"Yeah?"
"The second day of April Fools' has begun!"
"I honestly have no idea what you're talking about."
Why was she bringing up April Fools' all of a sudden? And why was there a second day? To begin with, it wasn't even April Fools' Day right now. Based on the seasons back in Japan, it was closer to November.
Well, Senpai seemed to live in some kind of special dimension, so maybe time flowed differently for her.
"Um, is today actually April Fools' Day in your world, Serious-senpai?"
Come to think of it, did her world even have one?
"Yes. To be precise, yesterday was April Fools'. And since I can only leave that room on April Fools' Day... well, I should have been automatically sent back once the day ended, but..."
"Wait, never mind the day ending. Senpai, didn't you just get here?"
She'd only been in my room for thirty minutes at most—it definitely hadn't been an hour, let alone a whole day. Not a single day had passed.
I suppose it was possible that time flowed differently where she lived, but in all our previous encounters, she had usually stayed for about a day. I didn't remember her ever disappearing so quickly.
When I pointed that out, Serious-senpai pondered it for a moment, then a look of sudden realization dawned on her.
"I-I see! This is... the Laws of In-story Time?!"
"Uh-huh?"
"Even if time passes in the Real World, a single day hasn't gone by in the story yet! Looking back, a decent amount of time usually passes during my visits, but this time, the progression has been modest. Therefore, a full day hasn't elapsed in-story yet!"
"So, basically?"
"A second day of April Fools' has been born!"
"No, it hasn't."
I could somehow force myself to wrap my head around the space-time distortion part. But no matter how warped time got, it shouldn't result in a second day of April Fools'. I was fairly certain the day after April 1st was just April 2nd.
"Heh... Hehehe... I see! If I use this law to my advantage, I can stay in this world even longer! My time has come! My spring is finally here—and that's no joke, even if it is April Fools'!"
"..."
I didn't really get it, but she seemed happy. At any rate, her expressions changed constantly and she took such erratic actions that she was at least interesting to watch.
When I got dragged into her pace, I ended up completely bewildered like I was just now. But since I didn't really understand Serious-senpai's existence to begin with, the correct answer was probably to just stop thinking too deeply about it.
Just as I was thinking that, a wall in my room suddenly slid open to reveal someone in a black Cat Kigurumi and a police hat.
"Hold it right there! That's quite enough plotting! The April Fools' Police won't let this slide any longer!"
"What are you even doing...?"
"Oops. I am Hatena. I am definitely not Alice-chan."
I'd only said "you," so she’d basically outed herself already. Regardless, Serious-senpai's face twisted in shock at the appearance of Alice... or rather, Hatena.
"What?! Have you sniffed me out already?!"
"Now then, why don't you head back to your room nice and quiet-like..."
"Ugh... D-Damn it! Not yet! My ambitions... I can't let the All-Humanity Serious-ification Project end like this!"
When did she get ambitions? This conversation was moving as fast as a Jet Coaster. And what on earth was the "All-Humanity Serious-ification Project"? Was she going to make everyone wear a serious expression? And more importantly, where did that "April Fools' Day Day 2" thing go?
"Ali— I mean, Hatena. Do you want some tea too?"
"Oh, yes please! And make it a mountain of Tea Sweets!"
"Also, before you go on with your little skit, put the wall back."
"Oka—y!"
The overall atmosphere was incredibly loose. Even though she was shouting about her ambitions, the whole thing felt more like a gag segment, so there wasn't a hint of tension in the room.
In the end, while still not really understanding what was happening, Serious-senpai returned to her seat and the three of us shared tea. After enjoying some small talk for a while, Serious-senpai eventually went back with Hatena.
...So, what exactly was "April Fools' Day Day 2" supposed to be, anyway?!
Serious-senpai (Affection Level MAX): "It was a good opportunity to feel a new possibility."
???: "By the way, what exactly is the All-Humanity Serious-ification Project?"
Serious-senpai (Affection Level MAX): "Who knows? I just said it on a whim..."