Remove netting from pork roasts, place in full-size 4-inch steamtable pans and cover two-thirds with water. Cover pans with foodservice film and foil and place in steamer for 5-6 hours, or until tender and the internal temperature reaches at least 145°F for 4 minutes. When tender, drain liquid, reserving all drippings. When cool enough to work with, but not cold, remove excess fat and then shred the pork by hand.
Mix Kikkoman Katsu Sauce with pork and add drippings back if needed for the pork and sauce to appear moist and juicy; refrigerate overnight.
Reheat pork in covered full-size 2-inch steamtable pans that are no more than half full, until the internal temperature reaches 165°F.
To serve, place 2 ounces of pulled pork and sauce on each slider bun.