The project is funded by JICA (Japan International Cooperation Agency) with a smaller (about one-fourth of project cost NRs 22 billion) contribution from the government of Nepal.

"A joint venture (JV) of Nippon Koei, Eight Japan Engineering Consultants, Nippon Civic Consulting Engineer in association with GEOCE Consultants, and ITECO-NEPAL is consulting on the construction project, while Hazama Ando Corporation, a Japanese construction company, is contracted for the construction..."

Details in the news source below.

https://theprint.in/world/nepals-first-transport-tunnel-being-built-with-japanese-loan-witnesses-major-breakthrough/2042526/