(Note: This may or may not be related to the main story. There's still a chance, but don't know if I should bring it to the main story.)
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Location: Eientei
*Boom*
The sound of explosion happened inside one of the room. Eirin and Reisen rushes towards the room and opens the door.
Reisen: Hime-sama! Kosaka-san! What happened!?
Kaguya emerges from the white smoke while coughing. For what reason Kosaka was there in the first place was because of weird request from Eirin.
Kaguya: *cough* *cough* *cough* *waving her hand from the smoke* I was trying to prank him by throwing a water balloon, but ended up messing with his work.
Eirin: *sigh and facepalm herself* Kosaka-san, are you ok? Actually, that was a dumb question, of course you're fine.
As the smoke begins to slowly dissipate, they are immediately caught off guard. They gasped once they see what is in front of them. There, standing Kosaka, but his body turned into a child, as in 5 years old. His appearance is still the same, but more adorable. For some reason, his clothes are still in the same size as his current body. By the way, if you're wondering where his weapons is, he didn't bring them.
Kosaka: hmm? *Tilts head*
He gives the girls an adorable tilt and innocent confusion look.
Kosaka: .... Onee-san?
After he said that, the three of them have blood running from their noses.
Kaguya/Eirin/Reisen (Mind): kawaiiiiiii!!!!!
Reisen tries to cover her nose and keeping her mind sane. She turns around and internally speaks to herself.
Reisen (mind): Calm down, calm down, he is nothing but a kid. But how? Wasn't he supposed to be immune? No, that's not important right now. I hope master will figure out some-
As soon as she turns around again to see the rest of them, she sees Eirin holding his hand while Kaguya patting his head. They're still having a nosebleed and didn't wipe it off.
Kaguya: Nee~ Kosaka-tan, how about you play with us onee-san?
Eirin: please, come with us to that room (bedroom) over there *point at where the room is* and we'll play together~
Reisen: *annoyed* *yell* Hold it right there, you perverts!
Timeskip: a few minutes later
They are now currently in the living room. On the table, there are some small meals for Kosaka to enjoy as he eats it in well-mannered attitude. Eirin tries to figure out and gives theories of how did he turned into a kid when he was supposed to be immune. As for Kaguya, she's still patting his head and fluff his tails. And for Reisen, she brought a paper fan to prepare if any of them do something perverted.
Eirin: I don't know, It's difficult for me to know his body's work. But more importantly, he will be back to normal size in a week or so.
Reisen: so we're just going to take care of him?
Eirin: Yes, that's right. Due to his fragile, defenseless, cute little body, we should be able to take care of him for a week.
Reisen (mind): *deadpan* Why were you saying that in suspicious way?
