Jones, who had a turbulent time in charge of England from 2015 to 2022, pulled out of his media duties for the day for health reasons, leaving assistant coach Neal Hatley to field questions on the side picked for Sunday's Test.
"Eddie will be there with bells on. You've known him long enough to know he's not missing this. It's just a precaution. He'll be fine for the weekend, no problems," Hatley said.
"He's unbelievably passionate about improving this Japanese team. He couldn't be more excited about coming to Twickenham. He looks forward to every game."
Jones has come under intense scrutiny for his management style after Danny Care said in his autobiography 'Everything Happens for a Reason', released earlier this month, that "everyone was bloody terrified of him".
The former England halfback added that the England environment under Jones was "like living in a dictatorship, under a despot who disappeared people".
Danny Cipriani, another England international, backed up Care's view in a recent interview.
Protocol dictates that teams should perform all media duties in person, but Japan have only been available online this week.
Hatley has worked under Jones with England, Australia and Japan and the scrum specialist does not recognise the allegations made against his boss.
"You vote with your feet and this is the third time I have had an opportunity to work with him and it is the third time I have jumped at it," Hatley said.
"I have enjoyed working with him immensely. He challenges me daily to be the best version I can be of myself and get the best version of the players.
"I have enjoyed my time immensely - it was a no-brainer for me."
