This is based sister my AO3 fanfics I made of the three, Konata, Kagami and Tsukasa (no Miyuki, sorry), 'Your Regressed Little Sister' and 'Tsukasa-chan, what's this?', which are two agere fanfics centred around Tsukasa. I recommend checking them out before roleplaying. Anyway, who do you want to be?
Konata: Tsukasa's caregiver, and calls herself her mommy. A hardcore otaku who doesn't really take her role seriously, but enjoys it nonetheless. Kagami: Tsukasa's sister and other caregiver. She was the first to find out about it and has a soft spot for little her, but sometimes gets mad at Konata. Tsukasa: The main little of the group. Mainly non-verbal and uses mainly diapers and pacifiers to regress, as well as cartoons. Very affectionate towards her caregivers.