A possible panda pregnancy at a Tokyo zoo caused stocks of a nearby restaurant chain to briefly soar 30% on Friday as the chance of a pandemic conception bred excitement among investors.

Ueno Zoo, which reopened on Friday after five months of coronavirus closure, said female panda Shin Shin was showing possible signs of pregnancy after mating with male Ri Ri in early March.

Tokyo governor Yuriko Koike delivered the news to media in a mid-morning announcement, which gave a welcome bump to shares in eateries near the zoo anticipating a visitor boom if a baby panda arrives.

The announcement comes as a rare spot of bright news for the Japanese capital, which is preparing to host the postponed Olympics this summer despite deep public opposition and coronavirus concerns.

Shares of Chinese restaurant chain Totenko spiked nearly 30 per cent before settling to around 1,109 yen, up 10 per cent from Thursday.

And French restaurant chain Seiyoken, also a celebrated establishment in Ueno, was trading up 7.8 per cent in the afternoon.

The announcement comes as a rare spot of bright news for the Japanese capital, which is preparing to host the postponed Olympics this summer despite deep public opposition and coronavirus concerns.

Koike warned that giant panda pregnancies are sometimes a false alarm, but voiced hope for a bundle of joy.

“Signs usually seen during a pregnancy are being seen now,” Koike said.

“It is still difficult to say clearly whether in fact a baby will be born... I am truly looking forward to being able to deliver good news to all of you,” she said.

Japanese media offers regular updates on the pandas at Ueno, which in non-pandemic times draw huge crowds of domestic and foreign tourists.

Xiang Xiang, a female born in June 2017 to Shin Shin and Ri Ri, was originally scheduled to be repatriated to China two years after its birth.