Rinse the Japanese Short-Grain Rice under cold water until the water runs clear, then cook according to your rice cooker or stovetop method; keep warm.
Make the kabayaki sauce by combining Soy Sauce, Mirin, Sake, and Sugar in a small saucepan; bring to a gentle simmer and reduce until slightly thickened and glossy (about 8–12 minutes). Taste and adjust sweetness or salt if needed, then remove from heat and keep warm.
Pat the Unagi dry with paper towels. If using whole fillets, score the flesh lightly to help the heat penetrate and the sauce cling.
Brush a grill or heavy skillet with Neutral Oil and heat to medium-high. Place the unagi skin-side down and cook until the skin crisps and you see the flesh begin to brown.
Flip the eel, then brush the flesh generously with the prepared sauce; continue grilling, flipping and basting every minute or two until the glaze is deeply caramelized and the eel is cooked through (about 6–10 minutes total, depending on thickness).
Transfer the glazed eel to a cutting board and let rest for a minute, then slice into serving portions.
Divide the warm rice into bowls, lay the sliced eel on top, and spoon any remaining glaze over the eel. Finish with a light dusting of Sansho to add a citrusy, slightly numbing aroma.
Serve immediately while hot—Unagi Kabayaki is best enjoyed fresh with the bright contrast of steamed rice and the lacquered, savory-sweet eel.
