Heat the oven to 350°F. Flake drained tuna into a bowl and mix with mayonnaise, celery, red onion, relish, lemon juice and pepper.
Split the connected Hawaiian rolls horizontally and place the bottom slab in a parchment-lined 9-by-13-inch pan. Layer half the cheddar, tuna mixture, and remaining cheddar; replace tops.
Brush melted butter over roll tops.
Cover with foil and bake for 15 minutes. Uncover and bake for 8 to 10 minutes until the center reaches 165°F and the cheese melts.
Rest for 5 minutes, cut into 12 sliders and serve warm.