A weird answer in that a few hours after the fact on a Sunday they randomly announce "nope, no evidence of this". It's practically impossible they queried every person who was possibly involved in this if it's real, so it's odd to see such a clear stance in claiming it's all lies. If the victim happens to have some proof, this statement will backfire spectacularly.
Ok, so this is how it would have gone:
Social media team within MarComms are made aware of the tweet.
They escalate to their team senior on duty at the weekend.
They will then have their own reporting tree for a situation like this, and will have contacted the senior management team & legal.
An HR person will have been tasked with reviewing submitted complaints - if theyre using a common HR system across Sony that would take about 5 minutes, as any filed communications would have been held digitally.
They didnt find any filed complaints, convey this to the legal & management team, the PR team roll up a statement, that gets approved by legal & sent out to relevant press contacts.
It very clearly states that there is no evidence of a complaint being made. My assumption would be Sony have a specific process for reporting workplace misconduct, that it was investigated if this process was followed, and the response based on that.