Today Koei Tecmo released their 2023 fiscal report and while things were down on their projections overall they at least seem happy about their biggest title, Rise Of The Ronin.
While they didn't release any specific sales figures they did say that Rise Of The Ronin, which is a PlayStation exclusive, was tracking ahead of their Nioh series. Nioh as a franchise has sold 7 million copies worldwide according to Koei Tecmo.

It should be noted that overall game sales for the company were down 11% from what the company expected citing "sales of new console and mobile titles" not reaching their targets. While the company didn't elaborate on what those titles are, Rise Of The Ronin was only out for a couple weeks during the fiscal year so it's unclear how much, if at all the lower sales were due to Rise Of The Ronin.
Koei Tecmo also made sure to point out how happy they are with Rise Of The Ronin's critical and user reception.

Earlier this month Koei Tecmo announced they were lowering their forecasts for the 2024 fiscal year due to "recent game launches resulting in lower sales than initially expected".
Regardless is seems like all things considered Koei Tecmo would appear to be happy with what they call their first AAA game.