Extra 2 – A Story He Likes (Patreon)

RAW

Author's Notes: Lately, I’ve been feeling under the weather, especially with some intense headaches, and I’ve been having a hard time organizing my thoughts properly for the main story…

So I’m really sorry, but for this time, please forgive me for writing an extra chapter that I just went with the flow on, without using my head too much.

I do plan to update the main story sometime next week.

(Maybe it’s because Shizuku is too tricky, and trying to tie her story together is giving me a fever from thinking too much?)

---

During the break, I watched Haruto leave the classroom, then walked over to Akagi’s desk—he’d been talking with him just a moment ago.

“Hey, hey, Akagi-kun.”

“Hm? What’s up, Tōjō-san?”

Akagi turned to me with a cheerful smile.

“So, um… I wanted to ask if you could tell me what kinds of topics Haruto likes to talk about.”

“Topics Haruto likes?”

“Yeah.”

Ever since we started dating, and even more so now that we live together, I’ve been talking to Haruto every single day.

But then I suddenly realized something.

He always adjusts the conversation to match my interests.

Talking to Haruto is so fun that time just flies by. And when I started thinking about why it’s so fun, I noticed that most of the topics we talk about are things I like.

Of course, it’s not just the topics that make our conversations fun.

The way he looks into my eyes makes my heart race, and how he responds so kindly and attentively makes me swoon...

Still, the truth is, Haruto is the one making the effort to match me. So this time, I want to be the one who matches him.

After I explained that, Akagi nodded and said, “Ah, I see.”

“Man, you’re so sweet, Tōjō-san. Haru’s one lucky guy!”

Even while saying that, he thoughtfully tried to come up with something.

“Let’s see… Haru’s into cooking, so maybe try that?”

“Ah, we actually talk a lot about cooking already, especially when we make breakfast together... So if you could give me something a bit more fresh, I’d be super grateful...”

I put my hands together apologetically.

Akagi didn’t look annoyed at all. “Gotcha, in that case…” he said and kept thinking.

Back before I started dating Haruto, I didn’t really have any connection with Akagi. Honestly, I kind of assumed he was just some loud, party-type guy.

But after actually talking with him, I realized he’s not just funny—he’s genuinely thoughtful and sincere, too.

Honestly, I kind of think he’d be a good match for Saki.

Though, if I told her that, she’d definitely say, “No way, absolutely not!”

Then suddenly, just as I was thinking about Saki and Akagi, he clapped his hands as if something had hit him.

With a mischievous grin, he leaned in.

“Okay, I’ll give you a topic that’ll make Haru go so into it you might actually be a little creeped out.”

And with that, I received a very special topic from Akagi.

—

After dinner, a bath, and brushing my teeth, I was all ready for bed when I quietly stood in front of Haruto’s door.

Heart racing with curiosity about how he’d react to the topic Akagi told me, I knocked.

“Haruto? Can I come in?”

There was a short pause before his answer came.

“Sure.”

I opened the door and stepped into the room.

He was sitting at his desk, probably studying like he always does before bed.

“I was just thinking… I’d like to chat a little before we sleep, is that okay?”

“Of course. Come here.”

He moved from his desk to the bed and gestured for me to join him.

Excited, I jogged over to sit beside him.

“So? What did you want to talk about? Is it about that outfit you were thinking of buying the other day?”

“Nope, today I actually wanted to ask you something.”

“Ask me something?”

The moment he tried to adjust to me again, I couldn’t help but grin.

Then, I dropped the topic Akagi had given me.

“Hey… is it true that when the Sun reaches the end of its life, it turns into a black hole?”

“Huh?”

His eyes widened slightly, and he looked genuinely puzzled.

Oh no, that expression is too cute! I wanna take a picture!

“Um… is that something you’re curious about?” he asked.

“Yeah. I read an article about it online today, and it made me wonder.”

The topic Akagi said would totally light Haruto up?

Space.

Apparently, when it comes to space, Haruto gets super excited and goes full-on science mode.

“Hey, Haruto. Will the Sun become a black hole someday?”

“Ah… that question… do you really want to know?”

“Yeah! I do!”

“Well then… the short answer is: no, the Sun won’t become a black hole.”

“Huh? Really?”

“Yeah. The Sun is just way too small for that.”

“Wait… the Sun is small?”

“Well, only when you compare it to the kinds of stars that do become black holes.”

“I see. Then… what will happen to the Sun when it reaches the end of its life? And what does that even mean—‘the end of its life’?”

I asked whatever popped into my head.

Haruto’s eyes changed in an instant. They sparkled like a little kid about to see their favorite hero at a live show.

Adorable…

“The life of a star, like the Sun, refers to the time it can continue nuclear fusion in its core.”

“Nuclear fusion…”

Akagi had warned me: “If you bring up space, Haru’s gonna go on this intense science monologue that’ll give you a headache—so brace yourself!”

But seeing him so excited? I wanted more.

Alright, Ayaka. Let’s do this!

“What’s nuclear fusion?”

His eyes sparkled even more.

“Nuclear fusion, simply put, is when light atomic nuclei fuse together to form heavier ones.”

“And what happens when the nuclei get heavier?”

“Energy is released. Right now, in the Sun’s core, hydrogen atoms are fusing into helium. And in that process, a tiny bit of mass is converted into energy.”

“Wait—mass is turned into energy?”

Mass means weight, right? So... some of the Sun’s weight is turning into energy?

“Let me explain simply. If a hydrogen nucleus weighs ‘1’, and two of them fuse into a helium nucleus, you’d think it’d weigh ‘2’, right? But it actually weighs around 1.8.”

Wait, what?! 1 + 1 = 1.8? That makes no sense…

“So what happens to the missing 0.2?”

“That’s what becomes energy. Mass is energy. That’s proven by the most famous equation from Einstein’s theory of relativity: E = mc².”

“Special relativity… Oh! I’ve actually heard of that E = mc² formula before. Is it really that amazing?”

“It’s incredible! In the equation, E stands for energy, m is mass, and c is a constant—the speed of light. It shows that energy and mass are interchangeable!”

Haruto’s excitement just hit a new level!

I might not get it at all, but I want to see more of this side of him, so I kept asking.

“So, if mass and energy can be converted, does that mean something amazing happens?”

“Totally! The speed of light is about 300,000 km/s. Squared, it’s an enormous number. So even a tiny bit of mass can become a huge amount of energy. That’s what happens in nuclear power. When uranium nuclei split, a tiny part of their mass disappears—and that becomes energy. I think it’s like… 0.1% of the original mass?”

Wow, he’s so passionate about this!

It’s like he’s on a science-powered adrenaline rush!

“And here’s the even more amazing part of E = mc²: if you have energy, you can actually create mass. Scientists have managed to create matter from pure energy in experiments!”

“Wh-Whoa! That’s… amazing! So… what does that experiment tell us?”

I have no idea what’s so amazing about that.

But Haruto’s excitement is so real, it must be something incredible.

“It gives us insight into what the universe was like right after the Big Bang.”

“The universe… right after the Big Bang…”

“Yeah! Back then, the universe was extremely hot and dense, and all matter existed as energy. As it expanded, the density and temperature dropped, and energy began transforming into particles. And with the help of the Higgs boson—a particle that gives mass to matter—electrons and quarks began to slow down and bind together, forming hadrons.”

Higgs? Quarks? Hadrons?

I’ve officially lost track of what he’s saying.

Time to bring this conversation back to something I can understand…

“W-Wow, hadrons are super cool! So, um, about the connection between nuclear fusion and the Sun’s life span…”

“Ah—sorry, I got carried away. So, the reason the Sun doesn’t collapse under its own weight is because of nuclear fusion.”

Wait—collapse? The Sun can collapse?

“What do you mean, collapse?”

“Well, the Sun’s mass makes up 99.86% of our solar system. It has incredibly strong gravity, and without the energy from nuclear fusion pushing back, it would collapse in on itself. That balance is what keeps it stable.”

“So when it can’t do fusion anymore, that’s the end of its life? And then it collapses?”

“Pretty much. Before that, it becomes a red giant. After that, it’ll become a white dwarf—a star that glows just from residual heat.”

I see… I have so many questions, but if I ask all of them, I think my brain might explode. I’ll just accept what I can for now.

“So that article I read saying the Sun becomes a black hole—that was wrong, huh?”

“Yeah. But it is true that some stars become black holes. If a star has about 25 times the mass of the Sun, it can collapse into one.”

“Twenty-five times the Sun… I can’t even picture that.”

“Right? The dividing line between neutron stars and black holes seems to be around that mass.”

“Neutron star?”

That’s new… and Haruto’s eyes just sparkled again!

“A neutron star is one step away from being a black hole. It’s the densest kind of star in the universe. Just a sugar cube of it would weigh billions of tons.”

“Whoa… and stars like the Sun become those when they die?”

“Exactly. They’re formed from supernova explosions.”

“Oh, I’ve heard of those! Giant explosions, right?”

“Right. Like I said, a star’s gravity is always trying to collapse it. Fusion pushes back. Heavier stars can fuse not just hydrogen, but also helium, carbon, oxygen—even iron. But iron is the most stable nucleus and can’t fuse. So once a star creates iron, it can’t generate energy anymore, and it collapses. The iron core gets crushed under pressure, and electrons merge with protons, forming neutrons. Those neutrons resist further collapse with something called degeneracy pressure, and then the star’s outer layers explode into space. That’s a supernova.”

“Wooooow! That’s… amazing!”

I have no idea what you just said.

But okay! Science is amazing!

“And if that ‘uncrushable’ neutron star still collapses, then it becomes a black hole.”

“Wait, I thought neutron stars couldn’t collapse?”

“They usually can’t. That’s due to the Pauli exclusion principle—it says that two fermions can’t exist in the same quantum state. That’s what creates degeneracy pressure. It’s represented using something called Grassmann numbers. Plus, there’s the Heisenberg uncertainty principle—Δx•Δp ≥ ħ/2—which means the more precisely we know a particle’s position, the more its momentum varies. So, neutrons packed tightly in a neutron star are basically going wild! That chaos becomes degeneracy pressure. But if the mass is too great, even that pressure can’t stop collapse.”

“I seeeee. Wow. Gravity’s… really something, huh?”

Pauli exclusion principle… sounds like a bakery name. Heisenberg? Fancy café, maybe.

“T-then what happens if a star collapses into a black hole?”

I managed to ask with what little brainpower I had left, and Haruto beamed at me.

Ahhh… just seeing that smile makes it all worth it...

---

"Tojo-san, were you able to talk to Haru?"

"Yes! We talked a lot! Thank you Akagi-kun!"

"That's good. So? Did you understand what he was saying?"

"Not at all! But you know, I think I've become a little smarter."

"Oh? Really?"

"Yeah. Well, E=mc2 is actually E=γmc2, and this γ is called the Lorentz factor...