Kousagi appears in a short manga published in the Materials Collection artbook, called "Parallel Sailormoon" In a parallel universe she's Usagi and Mamoru's second daughter. (The "ko" has nothing to do with Seiya.)

She's a happy-go-lucky child, who, according to her dad, has the talent for eating really bad food. Her tongue will one day "save the world." Like her mom and her big sister, she is clumsy whiny and a crybaby, even often dissed by her friends Ami, Rei, Mina, and Mako. (I can bet you can guess who their moms are. They look just like them too.) Also like her mom and sister, she posseses a hidden inner strength.

One day she encounters a nameless pink polka dotted cat. According to Kousagi, the cat is "the same color as the stuff you swallow at the dentist to practice brushing that makes your teeth turn pink. I hate that color." The cat gives Kousagi and her friends the power to transform into senshi to defeat a huge cat made up of a bunch of little cats, by ironically blasting them with a huge bunny. She isn't given a Sailor name, but she's often referred to as "Princess Kousagi." Her Sailor suit has rabbits on the tiara and the bow, and her she has four odango that match Chibiusa's.