TOKYO, Aug 3 (Reuters) - Shares of Japanese nursing home operator Nichiigakkan Co surged more than 8% on Monday after U.S. investment firm Bain Capital made a sweetened $1.2 billion offer.

Bain raised its offer price for Nichiigakkan to 1,670 yen from 1,500 yen after the market close on Friday as activist fund Effissimo Capital Management, which owns about 12% of Nichiigakkan, agreed to tender its shares to Bain.

Shares in Tokyo-based Nichiigakkan equalled the new offer price of 1,670 yen in early trade on Monday after rising 8.4%.

Hong Kong-based investment fund Lim Advisors, which owns a stake of an undisclosed size in Nichiigakkan, said on Monday the revised offer price remains substantially below fair value, which it estimates at about 2,400 yen a share.

Lim Advisors previously said Bain appeared to take advantage of coronavirus-related weakness in the share price it first launched a public offer in May. Bain Capital susbequently extended deadlines for the bid as the stock continued to trade higher than its offer price.

(Reporting by Junko Fujita; by Jane Wardell)