Catching a giant grouper needs a stroke of luck as well as good techniques and experience in catching big ones. Because the habitat of the giant grouper is very limited to rocky reef areas, you can not let it go even an inch after it grabs the bite.
Climate change may be responsible for the increasing number of catches of tuna in the pacific ocean. fishing yellow fin in the Sagami bay area in Kanagawa prefecture is getting the popularity, due to its size (10 - 40kg), among the anglers who want to catch a big one in the proximity of Tokyo. More and more blue fin are also caught by anglers off Oshima Island near Izu Peninsula. You can expect big ones weighing over 100Kg.
The same technique for Red Snapper can be applied to king fish. The main difference is their size and power. The biggest king ever caught weighed 37kg. Probably, a 5 kg-King is much more powerful than a 10kg-yellowtail.
King fishing basics:
Rod: 2.2 - 2.7m, slow-action, fiberglass, 12-20lb
Reel: 12-30lb
Leader line: 30 - 60lb tested, Fluorocarbon or mono, line length: 6-9m
Hook: "Hiramasa-bari" 13-17 gou