Side Effect: Breast Expansion

I let out a long breath.

"It's over..."

I sank to the floor as the tension drained from my body, watching the monster collapse beyond the window.

In my mind, Astra's dazzling figure from moments ago played on repeat—the way she'd been pushed back so hard, practically marching toward death, only to completely overwhelm the beast and take it down single-handedly.

"That power..."

Since she was the hero responsible for protecting the neighborhood where I lived, I knew a little about Astra. She was a rare elemental awakener, but her output wasn't strong enough to rise above C-class. That's where she'd stayed.

But the firepower she'd just used to defeat that monster was nothing like the Astra I knew.

It couldn't have been a dramatic awakening in the heat of battle... could it? I suppose it's not impossible.

I let out a deep sigh. Honestly, the moment I'd seen her unleash those brilliant golden lightning bolts, I'd understood exactly what had happened.

"Buff."

It was a strange ability that had attached itself to me one day. When someone ate my food, they received a buff—at the cost of a side effect. A unique form of superhuman power.

When I'd tested it on myself, it only improved my physical abilities a little. But with Astra, it had clearly manifested differently.

Any other explanation felt too perfectly timed to be a coincidence.

"Nom."

Recalling the scene, I took a sip of the soup Astra had left behind after her single bite. It had gone completely cold and didn't taste great, but the buff I'd imbued in the dish was still active. I could feel its power lingering inside me.

But...

"It's the same."

The only change I experienced was a slight increase in strength. Nothing like the explosive growth in ability that Astra had displayed.

Because she's a superhuman? Or is it simply a difference in gender? Or maybe this is what happens when anyone other than me eats it?

This was the first time I'd ever given my buffed cooking to someone else, so I was pretty confused. And I probably wasn't the ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠only one.

-Tap tap tap!!

Footsteps echoed from beyond the door, and then it burst open. A woman with dazzling golden hair rushed inside.

She was limping slightly, but her condition seemed much better than before. Astra spotted me immediately and fired off a question.

"You... that thing just now. That was your doing, wasn't it?"

She didn't spell it out, but both of us understood exactly what she meant.

I briefly considered playing dumb, but the certainty in her eyes made denial pointless. I nodded.

After all, I'd already resigned myself to this outcome the moment I'd offered her the buffed dish before she went off to face death.

"Probably."

"Probably?"

"I'll explain everything step by step."

I handed her a glass of water—she looked exhausted—and slowly told her about my ability.

I probably shouldn't mention anything about memories from a past life.

I skipped over the unclear memories of my previous existence and simply explained that one day, this unique power had appeared.

"A cooking-based ability that grants buffs to others...? I've never seen anything like that in the Association's database..."

Astra's expression grew increasingly bewildered as she listened.

I could understand why. A man—not even a woman—had awakened superhuman powers, and on top of that, it was a completely unprecedented ability. Of course she'd be shocked.

-Riiip!!

Hm?

As I gave her time to process my words, a sound like fabric tearing reached my ears.

The moment I tried to locate the source, Astra lifted her head, then bowed it again.

"I have a lot of questions... but first, I need to say this. Thank you."

"No, there's no need to thank me..."

I'd expected her to press for more details, but hearing gratitude first caught me off guard. I quickly helped her back to her feet.

"If anyone's thanking anyone, it should be me. You took down that monster..."

"That's my job. But you... um... what was your name again?"

"It's Siwoo."

"Right. Siwoo. You said you've been hiding this ability your whole life... and yet you used it for me."

I'd explained that I'd kept my power secret until now, so she understood my situation. Instead of lecturing me about the laws regarding unregistered superhumans, she chose to show understanding and offer thanks.

"If it weren't for you, Siwoo... I might have been badly injured or even killed fighting that monster."

"It wasn't that bad..."

"It was. Defeating that thing with my power alone would've been impossible. Thanks to you, I survived—and we prevented casualties among the civilians. Thank you."

"......"

She was a hero who fought for the people. I'd only cooked something to cheer her on, yet here she was, thanking me so sincerely. It felt embarrassingly awkward.

I'd been regretting revealing my hidden ability, but hearing her words made the regret vanish. Instead, I felt relieved.

If I hadn't taken the risk and given her that buff, she might have died or been seriously hurt. Using my power had been the right choice.

After the slightly uncomfortable silence passed, I asked the question weighing on my mind.

"So... what happens to me now?"

"Well..."

She was a hero affiliated with the Hero Association, and now she knew a man had awakened superhuman abilities. What would become of me?

Would I become the first male awakener and get subjected to all kinds of experiments to determine the cause? Or would they try to scout me into the Association as a hero?

The worries had started creeping in, which is why I'd asked. But Astra just gave me an awkward smile.

"I... I don't know either. This is the first time I've encountered anything like this."

"Ah..."

"I do run into unregistered superhumans during patrols sometimes, but they've always been women..."

Of course. How could she have experienced something like this before?

She was just as flustered as I was.

As the two of us sat there trying to figure out how to handle the situation, Astra noticed my slightly fearful expression. She clenched her fists and spoke first.

"You said you've been hiding your ability all this time, right?"

"Yes. Since there's no precedent for a man awakening, I was scared of what would happen if the truth came out..."

"Then... I'll keep it a secret for you."

"What?"

Astra was saying she'd conceal the fact that I was the first male awakener.

Was that even possible? Not reporting an awakening was a crime. And she was a hero working for the Association—could she really cover it up?

"Strictly speaking, the law only requires all awakened 'women' to report their status. By that logic, Siwoo, you're not a criminal."

...Was that true? I hadn't read the exact regulations, so I wasn't sure.

"Therefore, your awakening isn't a criminal record—it's simply the private information of an innocent civilian. As a hero, I can't just go around spreading that kind of information."

"But..."

"Besides... you've been hiding that power your whole life, and you used it to help me. I don't want to cause trouble for someone who's done me such a huge favor."

...She really was an angel.

I'd steeled myself, but I'd still been terrified about what might happen to my future. Astra had put my fears to rest.

"Is that... really okay?"

"Protecting citizens is a hero's duty. And you're one of the citizens I need to protect, Siwoo."

"Thank... you."

"I keep telling you, I'm the one who should be thanking you. As for how I defeated the monster... I'll come up with something to tell the Association."

Having eased my anxiety, Astra smiled brightly like before and raised both fists in a determined gesture.

-Jiggle!!

Ugh?

In that instant, her breasts bounced, and the hero suit clinging tightly to her body accentuated their shape, drawing my eyes like magnets.

What kind of thought is that toward someone who just showed me so much consideration...!

I desperately tried to think pure thoughts and quickly looked away.

...But had Astra's chest always been that big? And didn't her suit look even tighter than before?

"Oh, by the way..."

Just as I was focusing on that strange sense of unease, Astra clapped her hands to change the subject and asked another question.

"When you were explaining your ability earlier... didn't you mention there were side effects?"

"Ah."

The moment she said that, I remembered ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠something I'd completely forgotten.

My buff ability always came with side effects.

"Yes. Things like one toe going numb for two days, suffering from acid reflux all day, or losing your sense of taste for twenty-four hours..."

"That's unusual... There are abilities with recoil effects, but having fixed side effects like that is rare."

I listed all the side effects I'd experienced while testing the ability on myself. They only lasted a day or two at most, and none of them were life-threatening.

Just like how the buffs themselves weren't that strong, the side effects weren't particularly severe either... Wait ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠a second.

But my buff worked differently on Astra, didn't it?

If the buff manifested differently... didn't that mean the side effects might be different too?

-Riiip! Riiiiip!!

The moment that thought crossed my mind, the sound I'd casually ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠ignored earlier returned.

This time Astra heard it clearly too. She turned to look in the direction it was coming from.

...Her chest, stretched so tight it looked ready to burst.

"...Huh?"

Only then did she seem to notice the discomfort she'd been too distracted to register before. Astra muttered in a daze.

"Did they... get bigger?"

"What?"

Before I could even process what she meant, I asked again—and in that instant...

-Riiiiiiiiip!!!

The sound rang out loudly as Astra's suit tore apart.

And then...

-Jiggle!!♥

".....!!!"

The soft, bouncy marshmallows that had been hidden beneath were now completely exposed right before my eyes.

"........Huh?"

The information that flowed into my mind described a side effect completely different from anything I'd experienced before.