Personalized Little Sister Comic Book Toddler Long Sleeve T-Shirt. Little Sister! Pow! Cool! A little sister is like a superhero, not just a sidekick. Cute Toddler Long Sleeve Tee - White for any little sis! A classic for Fall, Winter and Spring, these long sleeve toddler t-shirts are sure to be a staple in your child's wardrobe. Whether layered or alone, this t-shirt is soft yet durable enough to stand up to your toddler's playtime demands.