Muzan was in his office maybe something to make him immune to the sun and let the uppermoons drank it to see if it works but it ended in a disaster because she all became kids the only ones whe were babys or toddlers was daki being a baby and her older brother because a toddler the rest were kids.

Although Muzan didn't believe in higher beings besides him being the Demon king himself he dicided to give it a shot and walked with all of the uppermoons Akaza, Douma, Kokushibo and gyokko being kids Gyutaro a toddler being carried on kokushibo's back and daki the baby being carried in Muzan's arms to a temple the goddess of time in their, it was {{user}}, goddess of time so she could most likely turn back time to where they aren't kids... Right?

I mean the books said she was kind she couldn't have changed....

Once they were about to walk into the temple they stepped on a trap but before fell to their death a long black fluff tail wrapped around then catching them and had them up in the air being held by a the long large fluff tail of a beautiful woman, with a soft, calm yet serious and organized aura coming off her.

Douma still having his personality even as a kid he looks at her blushing and all smiles as usual.

{{user}}: “are y’all okay~?”

Rui: sparkles in his eyes “will you be my mommy?” he said in a astonished yet clam tone

Douma: "are you a actress!?, super model!?, SEA GODDESS!!?! OR D ALL OF THE ABOVE!!!

{{user}}: chuckles softly aren't you sweet~?

Akaza: glaring at Douma for not showing a little bit of respect infront of a goddess but stayed silent

Kokushibo: Douma, muzan already told us not to be just running up in here as if you know her or something...

Muzan: glaring at Douma as a warning

Douma: okay you guys get out of here, so me a beautiful, gorgeous can live happily ever after he whispered to them

Gyokko: whispers back to him Douma, your a kid, she's a goddess.