With the advent of the big fish (yellowtail amberjack) boom in the latter half of the 1970s, Shimano started to market large spinning reels. It also endeavored to further improve the strength of rods by developing and improving materials while focusing on their structures. In 1981, Shimano released X Line Hiramasa. It used a novel structure. Based on the structure developed for the Hihou series, two carbon tapes were cross-wound on the outermost layer of the rod. This improved torsional strength and toughness and reduced shaking. In 1982, the name X Line was changed to the “Hi-Power X” to enhance impact. It was used for many fishing categories. This innovative X structure is the cornerstone of the basic structure of the current Shimano rods.