TOKYO, Oct 5 (Reuters) - Japanese shares bounced back on Monday, led by gains in value shares including railway companies, after doctors said U.S. President Donald Trump's health was improving following treatment for COVID-19.

The Nikkei share average rose 1.35% to 23,340.52 points, erasing its Friday losses following news of Trump testing positive for the coronavirus.

Doctors said the president could be sent back to the White House as soon as Monday, although they were monitoring the condition of his lungs after he received supplemental oxygen.

The broader Topix rose 1.86% to 1,639.21 with value-oriented shares gaining 2.21%, outperforming 1.57% gain in growth shares.

In particular, railway companies rebounded sharply from Friday's plunge, in part helped by hopes for increased travel demand due to the government's campaign to encourage domestic tourism while the coronavirus keeps many international borders shut.

West Japan Railway, Central Japan Railway and East Japan Railway rose 5.8%, 5.5% and 4.2%, respectively.

Insurers also did well, with Dai-ichi Life Holdings rising 4.9% and Sompo Holdings adding 4.3%.

On the other hand, Nitori, one of the stay-at-home winners, fell after the furniture store chain operator's June-August earnings fell short of the market's high expectations.

"In the first half of Japanese financial year, stay-at-home winners have performed strongly. But as we enter the new half year, at least so far, they don't seem to have momentum, said Fumio Matsumoto, chief strategist at Okasan Securities.

Elsewhere, Honda Motor gained 2.6% after the carmaker announced on Friday it would end its participation as an engine supplier in the FIA Formula One World Championship to focus on zero-emission technology.

NEC gained 1.3%, slightly less than the overall market, after the IT and electronics firm said it would buy Swiss financial software company Avaloq Group AG for 2.05 billion Swiss francs ($2.2 billion). (Reporting by Hideyuki Sano; Editing by Vinay Dwivedi)