Using the Note on Miia and Papi perhaps?

"Ms. Smith?" Kimihito asked as they say in his home, having gone back there after the incident. "How did you get Papi's certificate so quickly?"

"Hm?" Smith asked, looking up from her drink. "Oh, I already had it. Of course, the trouble was finding a host family willing to put up with such a frequent runaway. So we were just on our way here to **** you- er, ask you to take her in."

"YOU were the coordinator she ran away from?" Kimihito asked. He really shouldn't be surprised, Smith was the type to be lazy and inattentive enough to let that sort of thing happen. "Wait, does that mean?"

"Yep, welcome to your new home Papi!" Smith grinned.

Naturally, this led to Papi cheering happily, and Kimihito protesting, knowing full well how Papi and Miia had gotten along in the park, only to get blown off by Smith. Papi then started dragging Kimihito towards the bath, which Mia was surprisingly chill with.

"Oh? That's surprising," Smith remarked.

"Oh, you know, it's frustrating to have a stranger barge in, but hey, she's just a kid, whereas I am an adult who can control herself," Miia proclaimed.

"Oh, but Papi is the same age as you Miia," Smith corrected Mia, making her freeze up. "Harpies only look like they're that young. You see, they have small bodies to allow for flight...."

"Nevermind Darling, I'll take her to the bath!" Miia shouted, throwing the table at Kimihito.

"Gack!!" Kimihito cried out as he was laid out, and Miia hurriedly rushed Papi to the bathroom. "Ugh... So much pain..." Kimihito groaned, even as Smith laughed her ass off while making her exit.

Once Smith was gone, Kimihito managed to get up, and considered the situation. If Miia and Papi started fighting over him... He shuddered. Yeah, he could expect a lot of pain in his future... His imagination showed a Chibi version of all three of them, Papi having her harpy feet on his arms, and Mia holding his legs, and using him as a screaming rope in tug of war... He shuddered. "I'm doomed..." he wept.

He then paused, before pulling out the Sex Note. "... Or am I?" he asked. He realized he could use the Note on both of them, and have some fun with both... He then reflected that perhaps Miia's alteration of him with the Note worked a little too well if he was thinking like that, but he shook it off as perverted fantasies of threesomes ran through his head. Might be weird to include Papi on the fun, considering her appearance, but knowing she wasn't actually a child allowed him past that one.

He could eliminate any jealousy in Miia... He should probably make them both bisexual if they weren't already... Hmm, maybe give Miia a dominant position over Papi? He continued to consider how he should make his entry, before coming to a conclusion, and beginning to write.