1. Place grits in a medium bowl and add 2 cups water. Let grits soak at least 8 hours and up to overnight.

2. Drain grits and transfer to a medium saucepan. Add dashi and bring to a simmer over medium-high heat. Cook, whisking constantly, for 5 minutes. Add usukuchi, a large pinch of salt, and season with pepper. Continue whisking constantly until thickened, bubbling, and no longer grainy, about 10 minutes. Stir in butter until melted; season with salt and pepper. Set aside and keep warm.

3. Heat a large cast-iron skillet over medium heat. Add bacon and cook, stirring occasionally until it shrinks to about half its original size and is crisp and browned, 5 to 6 minutes. Remove bacon from skillet using a slotted spoon and transfer to a paper towel-lined plate. Drain fat and wipe skillet clean; set aside.

4. Place shrimp in a large bowl and add grapeseed oil; season with salt and toss to coat. Heat cast-iron skillet over high heat and add shrimp, working in batches if necessary. Press down on shrimp using the back of a spatula or a smaller pan to sear for 1 to 2 minutes. When shrimp look about halfway cooked, turn and press down on second side. Continue cooking until shrimp have just become opaque and have browned slightly. Remove from pan.

5. Divide grits evenly between 4 bowls; top each with a poached egg. Divide shrimp and scallions evenly between bowls and serve immediately.