Personalized Kawaii Backpack 100 Days Smarter Youth Long Sleeve T-Shirt. Youth Long Sleeve T-Shirt - White with funny kawaii cartoon backpack with eyeglasses and giant pencil says I'm 100 Days Smarter. Cute 100 Days of School gift youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)