I kinda had to make up some things about the dad's character(actually, all of it), so bear with me.
When Natsumi woke up the next morning, it was around seven thirty, but her dad wasn't here yet, so she went about making his favorite breakfast, tamagoyaki. If he was going to be here for once, she wanted him to feel at home.
Not long after she started making breakfast, Aki woke up and took over to apologize for making Natsumi do dinner. This was lucky, because Kioshii woke up moments later and began screaming. Natsumi rushed in to quiet her down, but Giroro was already there, offering Kioshii her bottle and cooing at her.
"Oh! Giroro, you didn't have to wake up! I was already up. I could have done it," Natsumi said. Giroro shrugged awkwardly.
"I don't mind," he said, looking back at Kioshii. Suddenly there was a knock at the door, and Natsumi panicked.
"That'll be dad! Stay here and keep her quiet, okay? Don't come out!" Natsumi said, and rushed out to open the door. Aki came up behind her, and Natsumi opened the door.
"Natsumi! You've grown! I've missed you!" Haru Hinata said, and rushed forward to crush the daughter he hadn't seen in years in a bear hug.
"It's good to have you home, Haru," Aki said, and he relinquished Natsumi just long enough to give Aki the same treatment and a kiss.
"Where's Fuyuki? Let me guess, still asleep, right?" he asked, shaking his head. "He's too much like me!"
"I'll go wake him up!" Natsumi said happily. Same old dad! She didn't know why, but she'd been afraid that he'd change while he was traveling.
Once Fuyuki was properly awake and dressed, he ran downstairs.
"Fuyuki! You're getting tall!" Haru exclaimed, catching Fuyuki as he tripped over the bottom stair in his rush. "Still as coordinated as always, I see," he teased. Fuyuki smiled sheepishly.
"So what is so important that I needed to come home two weeks early?" he asked. They stared at him.
"You were going to come home in two weeks?" Aki asked. Haru frowned.
"I forgot to call, didn't I. Sorry. Same old me, I guess!" he said. "Yeah, the paper's almost finished. But I have all the notes I need, so I'll be able to finish the paper here, where I belong. Although it's more of a book, at this point. I was thinking of getting it published!"
"That's great, dad!" Fuyuki exclaimed. He would be the one to be excited. While Natsumi looked like her dad and acted like her mom, Fuyuki looked like his mom, and acted like his dad.
"So what happened?" Haru said.
"Where to start!" all three of them exclaimed together, and they started laughing. Haru, sensing the news wasn't bad, relaxed a little. They ushered him into the living room and they all sat down.
"Do you want the basic idea, or details?" Aki asked.
"Why not give me the basic idea and add in details gradually? My brain will be able to process more that way," he said jokingly.
"Well, the simple idea is we have some new roommates, in a way," Natsumi said.
"It can't be that simple, or you wouldn't have had me come back. You would've just told me over the phone," Haru said suspiciously.
"Well, they're a bit strange. And, not human," Fuyuki said bluntly. Haru stared at him.
"You don't expect me to believe Mom let you get pets?" Haru asked, looking into each of their faces in turn. Aki smiled.
"It's a bit more complicated than that, dear. Maybe we'd better introduce them. Natsumi, you get Giroro. Tell him to leave that other one in there for now. Don't want to overload his mind. Fuyuki, go get the others, all right?" Aki commanded sweetly. The kids rushed to do their job.
"Others? How many are there?" Haru asked. A sinking feeling started when Aki had to stop and count on her fingers.
"Um… six or seven, I think. But one of them will have to wait until later. She's a special case," Aki replied.
"Six or seven! How do you fit them all in the house? We don't have any spare bedrooms!" Haru exclaimed.
"Well, only four of them live here. (Giroro, Keroro, Mois, Kioshii) The rest just spend most of their time here! (Tamama, Kululu, Dororo) And we've had some… uh… remodeling done in the basement. (the base)"
"Still!" Haru exclaimed, skaking his head. He was getting confused.
"Also, they don't take up much room. They're pretty small. Well, all but one of them, anyway. (Mois)" Aki said.
"You didn't adopt, did you?" Haru asked, trying to imagine it. It wasn't working for him. Aki laughed.
"Not in the way that you mean, no. Oh, here they come! This may come as some of a shock…" Aki said apologetically. All six aliens (Kioshii doesn't count. She's half-alien. Also, she was left in the room with a binky to be brought up slowly at a different time) walked slowly into the room, followed by Natsumi and Fuyuki.
"Kukuku…" Kululu said, turning Haru's head in the direction of the aliens. He whitened. "So this is Mr. Hinata. Interesting."
"What is that?" Haru asked, eyes wide. Tamama bounded up to him.
"So you're Fuyuki's papa? You don't look much like him!" he said. Haru shrunk back a little.
"What are they and how can they talk?" Haru asked, his voice fighting to maintain steady.
"We are the Advance Recon Mission Prepatory Invasion Terror Platoon of Keron, the 58th planet of the Gamma Planetary System! And to answer your second question, satellite TV!" Keroro announced.
"That's just uncle's super-duper way of saying that we're aliens!" Mois said. (she was already in alien form)
"Aliens?" Haru whispered weakly. Aki put a hand on his arm reassuringly.
"We come in peace!" Dororo said, smiling at Mr. Hinata under the mask.
"Ha. Speak for yourself, hippy," Giroro said, shaking his head. Natsumi sighed.
"It'll take some getting used to, dad. Trust me," Natsumi said.
For the next hour or two the presence of the frogs was explained to the bewildered father, interrupted only by Natsumi and Giroro sneaking away to check that Kioshii stayed asleep or occupied until it was time to introduce her. By the end of the conversation, Haru had much the same reaction as Fuyuki had.
"So my theories are all correct! Aliens DO walk among us!" Haru said triumphantly. This was old news to everyone present, but they didn't bother dampening his spirits. Kululu started to, but Natsumi punched him in the back of the head to shut him up.
"Unforgiveable!" said Omiyo (google it), rising from the floor. "Weren't you going to introduce me, too?"
"A ghost! Our house really was haunted?" Haru asked. Now that he'd been surprised, the paranormal stuff stopped bothering him."No wonder we got it so cheap! This paranormal stuff has been swarming around you guys, hasn't it?" Everyone nodded.
"And Natsumi, where do you and the little pink alien keep sneaking off to?" Haru asked. He had Fuyuki's powers of observation and detection.
"I am not pink!" Giroro exclaimed as the other frogs laughed at him.
"Um, nowhere?" Natsumi said, smiling innocently.
"There's one more thing you'll need to know, which is where she's going, but you might want to get used to this first," Aki suggested.
"After all that, I think I can take anything!" Haru exclaimed.
"Well, if you say so… Natsumi, go ahead and get her," Aki said, still unsure.
"Oh, I'm going to meet the seventh one, now? The 'special case'?" he asked. Aki nodded. Natsumi and Giroro went to get Kioshii. Natsumi carried her with the sling and put her binky in her mouth. She was no longer asleep, but still out of it. Taking a deep breath, Natsumi whispered down to her.
"Ready to meet grandpa?"