The opening session of the test on Saturday morning was brought to an early end after the Mugen NSX-GT's left-rear tyre let go in spectacular fashion along Fuji's start/finish straight, leaving debris all over the track.
Ukyo Sasahara was at the wheel when the deflation occurred, although he was able to bring the Mugen NSX-GT to a controlled stop after the puncture.
The damage was also sufficiently minor that the #16 car was able to run in the afternoon session.
Dunlop says it is still analysing the cause of the failure, but had yet to come up with an explanation a day on from the incident.
"We are checking the tyre and we don’t see anything different from other tyres," Dunlop Japan's motorsport department manager Yoshinao Yasuda told Motorsport.com.
"We had suspected there was a production problem, but looking at the data we can’t see any evidence for this, so we don’t know the real reason.
"For now, we are asking [Mugen] to bump up the tyre pressure a little bit and run with less camber."
Asked if debris had been ruled out as a possibility, Yasuda replied: "It's possible, but we haven’t seen any evidence for it."
Although Yasuda revealed that the tyre had been deflating since Turn 10, Sasahara told Motorsport.com that he had no warning of the impending deflation.
He added he felt lucky that he wasn't injured by any flying debris, given the drivers' side door was forced open by the puncture.
"I didn’t expect it all," recalled the Japanese driver. "I just felt the tyre pressure was maybe getting a bit low exiting the last corner and then suddenly it blew up.
"I was so lucky that I didn’t hit anything, and that the damage was quite limited. The body on the left-hand side from the door back was destroyed, and also the force of the tyre opened the door.
"I think this is why people were worried about me, but actually I was fine. Just some small part of the tyre scratched my [helmet] visor. Afterwards when I saw my helmet, it was quite scary. I was lucky not to be injured."
The Mugen car shared by Sasahara and Toshiki Oyu ended up 13th-fastest on Saturday, a little over a second off the pace set by TOM'S Toyota man Sho Tsuboi.
