Mizuho service at Kumamoto, hauled by an ED76 electric locomotive, 1987
The Mizuho was first introduced on 1 October 1961 as a seasonal limited express sleeper train service, which ran from Tokyo to Kumamoto in Kyushu, supplementing the three existing limited express services, Asakaze, Sakura, and Hayabusa, operating between Tokyo and Kyushu. From 1 October the following year, the service was upgraded from a "seasonal" service to become a daily service.
The typical formation at this time was as shown below, with car 1 at the Kumamoto end. Cars 8 to 13 ran only between Hakata and Tokyo.
From 1 June 1963, 20 series coaches were added to the formation, and the train divided and joined at Moji to serve Oita via the Nippo Main Line in addition to Kumamoto.
On 20 October 2010, it was formally announced by JR West and JR Kyushu that the Mizuho name would be used once again from 12 March 2011 for the new limited-stop shinkansen services operating between Shin-Osaka and Kagoshima-Chūō using new JR West and JR Kyushu N700-7000 and N700-8000 series 8-car trainsets with a fastest journey time of 3 hours 45 minutes, some 25 minutes faster than the Sakura services.
Trains stop at Shin-Kobe, Okayama, Hiroshima, Kokura, Hakata, and Kumamoto only, running at a maximum speed of 300 km/h (190 mph) on the Sanyo Shinkansen and 260 km/h (160 mph) on the Kyushu Shinkansen. The services are aimed primarily at the business market, with two return services in the morning and two in the evening. On 2014, one of the Sakura services has been speed-up and converted into a Mizuho, bringing the total to six return services a day. Two of these Mizuho return services will also begin stopping at Himeji now, improving convenience for passengers in the western part of Kansai.
Like the Nozomi service that operates on the Tokaido and Sanyo Shinkansen, the Mizuho is not valid for tourists traveling with a Japan Rail Pass.