Wow it's been a loooooooong time since I've wrote anything, even longer since I've uploaded something. I've really gotten into Osomatsu-San lately and finally got inspired to write some fics again, so this won't be the last thing I write. This one in particular was inspired by an RP with a friend, it was just so cute. ;-;

Things in square brackets are in English.

Karamatsu woke up feeling refreshed after a good night's rest. He sat up and stretched.

"Morning [brothers]! It's time to wake up as the sun smiles upon us!" He smiled, looking at his siblings, hoping they felt as refreshed as he did.
"...Let me sleep nii-san...Hm...That's odd...The futon feels more spacious?" Todomatsu said sleepily and proceeded to roll away from Karamatsu in order to see how much room he had gained overnight. "Eh? Where's Oso-nii?"

The others then looked at the spot where Osomatsu usually slept, he really wasn't there which was unusual considering the fact that they usually got up together.

"Eh!? Where's nii-san!? Did you shrink!? Are you under the covers!?" Jyushimatsu sat up quickly and pulled the covers off everyone. "AHH! Nii-san's not here!? He left early!"
"That's weird..." Choromatsu mumbled quietly, sitting up. "It's not like Osomatsu to be up before everyone."
"He probably snuck out to play pachinko and take our money before we woke up or maybe there's a horse race on today?"
Todomatsu sighed, he really hoped that wasn't the case as he earnt that money himself, but still it was hard to think of any other reason for Osomatsu to not be around so early in the morning.

That got everyone up, it was just like him to take their money so he could gamble, like the one time they were all sick and instead of taking care of them, he took their money, hoping to win and make them feel better, although he probably would have kept those winnings for himself, who knows why he'd think that would work. The five remaining Matsu brothers swiftly moved to where they kept their wallets and found that they were all still there, including Osomatsu's. They all immediately knew something was off, just what was Osomatsu doing out so early? They got dressed and went to have breakfast, he wasn't there either. They searched the whole house for him, Osomatsu had left the building, his whereabouts completely unknown.

Seeing as there was no clue to what Osomatsu was doing up so early, the five brothers just decided to get on with their day, they'd just have to ask him what he was doing later when he got home. Hours went by and the brothers ended up eating lunch minus the eldest. It was about 2.40pm when they were all chilling in the living room, feeling bored when Karamatsu spoke up.

"Hmm...It seems Osomatsu hasn't come back yet, that's strange..."
"He's probably playing pachinko or at the horse races." Todomatsu repeated his thoughts from earlier, while texting on his phone.
"Totty, he left the house without any money! There is no way he could be at either of those places." Choromatsu frowned at him in frustration, then sighed. "I just hope he hasn't gotten himself into trouble..."

Before anything else could be said, the house phone rang. The brothers looked at each other hesitantly, maybe Osomatsu really had gotten into trouble and this was someone calling them to let them know of the bad news.

"Maybe...That's him calling now?" Todomatsu tried to sound positive, though they all knew it obviously wasn't Osomatsu, himself, he had no mobile phone of his own nor did he take any money to use a phonebox.
"Karamatsu, get the phone." Choromatsu ordered, looking back at his computer screen. He was worried he'd jinxed it with what he'd just said, but he also didn't want to miss out the new Nyaa-chan merch he was waiting for.
"Yes, my [brother]! I'm sure that it's nothing to worry about!" Karamatsu got up, hoping his words eased the tension, but the glances between them made it clear they either didn't believe him or simply weren't listening as usual.

Karamatsu brushed it off, thinking they were just struggling to believe this phone call was anything but something bad about their eldest brother. He almost hesitated to pick up the phone himself, unable to also feel a small amount of dread.

"Hello, Matsuno residence, how may I help you dear caller?"
"Ah, hello which of the Matsuno brothers is this, dasu?" Dekapan responded, Karamatsu knew it was unusual for him to call.
"Karamatsu! Do you need Jyushimatsu's assistance? I can go and get him?" "Hello Karamatsu, No, no. I think you may actually be the best one to talk to about this, um...I'm calling because a slight incident occurred with Osomatsu, dasu."
"Huh? Osomatsu? What happened!?" He hadn't realised it, but Karamatsu's voice was loud, his worry for the eldest clear, his usual facade broken.
"Sounds like Kara-nii may be talking to Oso-nii..." Todomatsu said, his tone uncaring, clearly more interested in his phone.

Choromatsu looked at his youngest brother with a frown again.

"Pretty sure it's more likely to be someone calling about Osomatsu, there's no way he could call us on his own."
"You don't think he's..." Ichimatsu mumbled quietly.
"No, no! I'm sure he'll be ok! He always bounces back from whatever happens." Choromatsu tried to reassure them all.

"He's not hurt exactly, though he is rather upset dasu. You and your brothers don't need to worry he's safe. However, um..." Dekapan hesitated, unsure of how to put it. He could tell that the young man was worrying more than he let on.
"Please...Tell me what's happened to him." Karamatsu whispered, his words only just being picked up by the elder man.
"Well...To put it simply...Osomatsu is now a toddler."

Karamatsu widened his eyes in surprise, unsure if he heard him properly. So, in a way he was the eldest now? Was that right? That's going to be something that'll take time to get used to, that is if he isn't changed back soon.

"...Can you please repeat that?"
"Osomatsu Matsuno, your eldest brother...Was turned into a toddler."
"[Oh my God]! How did that happen!?"
"...Things. I'm sure you are aware of the kind of things that could happen at my lab. Could you please come and collect him? I think it would be best for Osomatsu to explain himself. Right now I think he needs his brother's company. Unfortunately I do not have a cure right now, so someone needs to watch over him dasu."
"[Of course]!" Karamatsu posed, even though he could not be seen, trying to keep up his cool facade. He somewhat hoped that if the others were listening, their worries would be relieved.
"Come quickly dasu." Dekapan responded, then hung up.

Karamatsu hung up the phone and poked his head through the door to where his younger brothers were waiting for the news.

"That was Dr. Dekapan...He requested for me to go and collect Osomatsu."
"Eh!? That's a weird place for him to go...What was he doing there!?"
"I think it's best we explain later, but [no worries] for he is safe!" Karamatsu smirked, which made Todomatsu sigh.
"I guess he must be if you're sticking to that painful facade..."
"[Farewell]! We will be returning soon!" Karamatsu left the house, his confident smile turning into a worried frown.

Did he really hear correctly? No way could that be true, right? Surely Osomatsu had just got him in on some kind of prank. He knew Dekapan had a lab full of unusual, yet amazing things from personality altering caps to medicine that could allow cats to talk and understand a human's true intentions, but Osomatsu turned into a toddler? That just seemed too farfetched, why would Osomatsu want to do that? But he couldn't ignore the request to go to the lab, maybe something really was wrong?

Soon he found himself at Dekapan's lab, he supposed getting lost in thought allowed time to pass quickly. He entered the lab and posed in one of his usual painful poses, hoping to reassure all who were there.

"I have arrived!"
"Painful." Was the response he heard, from a vaguely familiar voice.

Karamatsu looked at the source, there he was. Osomatsu stood there before him in nothing but his usual hoodie with their family symbol on it. Dekapan hadn't lied, Osomatsu had turned into a young child no more than 3 or 4.