our BABY sister

Yui Sakamaki is the youngest of the sakamaki's and the only girl living with her 6 older brothers, this young vampire and her older brothers live in a mansion secluded form the rest of the world being the creature of the night. What happens when the second eldest Reiji gives Yui a potion putting her back into her five year old body and how will her bothers react trying to keep their five year old cute sister out of trouble.