The Second Songhua River in the former Manchuria with a width of 700m-800m. In 1936, a project was launched to build the "Fengman Dam" on it. It was a concrete gravity dam with an embankment length of 1,100 m , a height of 91 m, a crest width of 8 m, a volume of 2.2 million cubic m and a foundation excavation volume of 1.9 million m3, making it the world's largest dam after the Hoover Dam and Boulder Dam (as they were known at the time of construction).
In 1939, cofferdam construction on the left bank began. However, underwater concrete construction in the extreme cold was very difficult. Snake baskets, boulders, and other obstacles froze on the river bottom on the way to the connection of the right bank cutoff, and were not easily removed.

A series of large-scale natural disasters, including the Makurazaki typhoon in 1945, encouraged a government-led flood control project for major water systems in 1949, prompting a shift to a multi-purpose dam system, including water resource development. At the same time, the Tone River in Gunma Prefecture, which suffered typhoon damage for three consecutive years, experienced flooding of its main stream and tributaries, causing extensive damage to nearby areas. Daiho Corporation began construction work on the revetment in 1948, but the large typhoons hitting the area every year caused damage. We determined that the problem could not be addressed by existing construction methods. Then, an on-site chief engineer proposed the Simplified Caisson Method devised at the Fengman Dam , and it was adopted for the first time in the postwar period for revetment construction.

The Daiho Pneumatic Caisson Method was revolutionary. It used an airlock in a double-slab structure made of reinforced concrete to carry out excavated earth and perform pressurization and depressurization. However, with declining steel costs and other factors, steel locks became popular for on-site installation due to their simplicity. The Daiho Pneumatic Caisson Method fell out of fashion. At this time, a project to build a huge suspension bridge in the Tokyo Bay area emerged. Amidst increasing demand for further safety assurance, work environment improvement, and cost reduction, our pneumatic caissons were extended to greater depths and large-scale caisson construction increased, leading to the adoption of double slabs as the Japanese foundation for suspension bridges.

In 1997, the conventional "Daiho Pneumatic Caisson Method” was renewed. “DREAM II Multi-functional Caisson Excavator” was developed, which can be remotely operated, to excavate a wide range of soil types, from clay to sand and gravel layers and bedrock. This has further improved the working environment and other aspects of workers' lives, enabling them to work safely and securely. Rock excavation was successfully completed by adopting this technology in the construction of Mabechi-gawa River Bridge (substructure construction) on the Tohoku Longitudinal Expressway in the same year.

We have had a deep relationship with the Republic of Madagascar since 1977, when we participated in the Namorona power plant project as an Official Development Assistance (ODA) project. Since then, we have been involved in many infrastructure facilities, including road construction and water supply projects. In 2006, we engaged in the "Comprehensive Growth Project, District Port of Ehoala Construction Work" (Port of Ehoala project). It was construction of a new port with a quay depth of 17.4 meters to offload the titanium ore reserves near Fort-Dauphin, southeastern Madagascar, into Galison bay.

The Double-slab Advanced Unmanned Pneumatic Caisson and NewDREAM Method are used to not only perform unmanned excavation by remote control, but also daily inspection and maintenance of the excavator at atmospheric pressure, achieving a significant reduction in work under high pressure and preventing health hazards due to compressed air. In addition, an unmanned ground test was conducted upon completion of the settlement to confirm the ground bearing capacity and completed the shaft at great depth.

Because of years of public investment decline and the economic downturn triggered by the Lehman Brothers collapse, the construction industry has been restricting the hiring of personnel. As such, there is a shortage of engineers to meet the demand for earthquake reconstruction and the Olympic and Paralympic Games. In 2015, we separated the Human Resources Department from the General Affairs Department to strengthen recruitment. We continue to offer internship and work experience programs to provide an opportunity for people to experience our workplace atmosphere. We have also reviewed the recruitment plan and currently hire around 40 new graduates every year, regardless of the economic climate. We also strive to correct the imbalance in our employee composition.

With reliable technology to meet our clients’ trust, Daiho Corporation has been contributing to society. We have been involved in many construction projects around Japan. Bridges and structures constructed using the Pneumatic Caisson Method suffered almost no damage in the Niigata earthquake in June 1964 and the Southern Hyogo Prefecture Earthquake in January 17, 1995. Caissons have attracted attention as they proved to be indispensable structures in Japan that are more earthquake-resistant than expected.

Torrential rains associated with climate change have increased in recent years, and we recognize the urgent need to minimize damage from flooding in urban areas where underground spaces such as underground malls and subways are expanding. We have been committed to disaster prevention and mitigation projects by utilizing Daiho’s unique and specialized technologies, such as the Pneumatic Caisson Method and Shield Method. A phantom river that appears “UNDER RIVER” only with heavy rainfall is the concept of our underground rainwater storage facility. We created a concept video and a special website to explain the significance of its existence.