NSG owns NH Techno Glass jointly with Hoya Corp . It was not immediately clear whether Hoya would sell its stake if there was a high bid, or hold onto it.
Global private equity firm Carlyle Group [CYL.UL] is rumoured to be interested in acquiring the company.
NSG bought British glassmaker Pilkington for around $3 billion in 2006 and may use funds from the sale of NH Techno Glass to pay back some loans.
It had debt of 560 billion yen as of March and a debt/equity ratio of 1.66 percent. NSG's stated aim is to bring this down sharply to 1 percent by 2011.
Privately owned NH Techno Glass group's head office is in the Japanese city of Yokohama. It has affiliates in Singapore, Taiwan and South Korea.
The company fell on hard times after problems on its production line. In September 2006 it took action and started to cut some loss-making products and jobs, resulting in a move back into the black.