Personalized Kawaii Backpack 100 Days Smarter Youth T-Shirt. Youth T-Shirt - Black with funny kawaii cartoon backpack with eyeglasses and giant pencil says I'm 100 Days Smarter. Cute 100 Days of School gift Let the good times roll in a durable T-Shirt that takes kids from school to play in an amazing array of colors. 5.0 oz., pre-shrunk 100% cotton. Seamless 1x1 rib collar.