It will take a 60% stake in the venture, while partner Sino-Thai Engineering & Construction will hold a 40% interest, according to a statement to the Stock Exchange of Thailand.
They will invest roughly ¥61.24 billion ($539.7 million) in the project, which will be built on a 332.8-hectare site.
The two companies will acquire PurpleSol, which holds an approval from the Japanese government to build the project, as well as landowner SolarOne.
Thai Solar Energy now owns 135 MW of solar capacity, with 98.5 MW of it in Thailand.
A growing number of Thai industrial groups have moved into the Japanese solar market over the past year, mainly by buying up government approvals for unbuilt projects.
Last April, Global Power Synergy (GPSC), a subsidiary of Bangkok-based oil and gas producer PTT, invested $89 million in a 20.8 MW solar project in Ichinoseki, Iwate prefecture. It aims to complete the project by the end of this year.
In August, Bangkok-based Gunkul Engineering revealed that it had chosen Toshiba to provide EPC services for 33.5MW project it is developing in Kimitsu, Chiba prefecture.
And in October, a unit of Thai mining firm Padaeng Industry finished building a 2.27 MW array in Nanao, Ishikawa prefecture — its first PV project in Japan.