Japanese title: おかぐやさん (OKaguya-san)
Artist: komaku juushoku

Kaguya (with help from the rest of the Eientei gang) takes care of baby Keine and Mokou.

Summary
Part 1 - Kaguya tries to bathe baby Keine, to Mokou's resistance
Part 2 - The babies try to say all the Eientei gang's names
Part 3 - Baby Keine gets up early to see off Udonge
Part 4 - Kaguya teaches baby Mokou to be more gentle
Part 5 - Kaguya falls asleep. Keine to the rescue!
Part 6 - Some time has passed, Keine and Mokou are now little girls
Prequel - A story explaining how the scenario happened
Part 7 - The Eientei gang try to calm down a crying Keine
Part 8 - Halloween babies
Part 9 - Revenge of Halloween babies

Related series
Baby Keine! - Adult Mokou takes care of an infant Keine
Remiliamama - Remilia takes care of baby Patchouli and Sakuya