Daini developed the 45KS to challenge in-house rival Suwa Seikosha's Grand Seiko line for technical dominance. It features a Hi-Beat 36,000 A/h movement like the contemporary Grand Seiko 61GS from Suwa, albeit still hand wound. This same movement, the Seiko 4500, was also used in Daini's own Grand Seiko 45GS, which was produced at the same time. The primary difference was case finishing and the accuracy of the movement Grand Seiko models went beyond chronometer grade, while only some King Seiko movements could reach that level of accuracy.
The 45KS line was produced from the height of the classic mechanical watch period through the quartz crisis before petering out and ending production in the early 1970's. It was the last hand-built King Seiko, with the King Seiko 56KS and King Seiko 52KS using highly-automated movements for reliability. It was also the last of the 36,000 A/h movements from Daini.
The 45KS lineup was mostly traditionally-cased, with just a few options available. The majority of 45KS models feature “Grand Seiko Style” cases reminiscent of the legendary Grand Seiko 44GS from Daini, with only the pillow-bodied -8000 and curving -8010 models really deviating. All featured simple faces and hands and a golden “KS” medallion on the case back, a feature later removed from the line.
The 45KS line used Daini's 4500 calibre, a hand winding “Hi-Beat” chronometer. This is the only King Seiko model to offer a 36,000 A/h movement All later “Hi-Beat” King Seiko models oscillated at 28,800 A/h. The King Seiko mainly used the basic “45” model with no day or date or the 4502 model with date only.