Nippon Kogaku was not one of the companies originally involved in the development of the vertical-travel shutter.
In 1962, however, they did release a camera called the Nikkorex F, which had a vertical-travel shutter with sectional steel blades, so Nippon Kogaku did realize the value of the shutter fairly early on.
In 1965, Nippon Kogaku incorporated a sectional-blade vertical travel shutter unit in the Nikomat (Nikkormat) FT / FS.
In fact, the shutter units contributed greatly to the popularity of those cameras.
Business was booming for TTL SLR cameras back then. One reason for the success was the popularity of various manufacturers' focal-plane shutter SLR cameras, including the Asahi Pentax SP (1964), Canon PELLIX (1965), Canon FT (1966), Topcon RE Super (1963) and Minolta SRT-101 (1966).
Each of these cameras used a horizontal-travel shutter with cloth curtains.
The Nikomat FTN, a modified version of the FT, and the Nikomat-series cameras that followed each employed a vertical-travel shutter, as did the Konica FTA (1968) and ensuing models.
Naturally, surrounded by SLRs that featured horizontal-travel shutters, the Nikormat and Konica cameras stood out.