Step 1: Rinse the sushi rice under cold water until the water runs clear. Cook the rice with 2 1/4 cups of water in a rice cooker or on the stovetop.
Step 2: While the rice is hot, gently fold in the mixture of rice vinegar, sugar, and salt. Let the rice cool to room temperature.
Step 3: Finely shred the imitation crab sticks using your hands or a fork. Mix the crab with Kewpie mayo, Sriracha, and sesame oil in a medium bowl.
Step 4: Place a sheet of nori on a bamboo sushi mat. Spread a thin layer of seasoned rice over the nori, leaving a small gap at the top edge.
Step 5: Place a line of the spicy crab mixture (and any optional vegetables) across the center of the rice.
Step 6: Use the bamboo mat to roll the nori tightly over the filling. Use a drop of water to seal the edge of the nori.
Step 7: Using a sharp, wet knife, slice the spicy crab roll into 6-8 pieces and serve immediately.