Combine the ground beef, breadcrumbs, egg, half the teriyaki sauce, crushed pineapple, onion, garlic, salt, and pepper in a large bowl. Mix until evenly blended but do not overwork the meat.
Shape the mixture into a loaf that fits inside your slow cooker. Place the loaf directly in the cooker.
Cover and cook on low for 6 hours until the internal temperature reaches 160 degrees.
Brush the remaining teriyaki sauce over the top of the meatloaf. Sprinkle the sesame seeds evenly across the surface.
Cover again and cook for 15 more minutes to set the glaze. Let the meatloaf rest for 5 minutes before slicing.