The Japanese striker made the switch from Stuttgart to Mainz in the summer of 2013 and has gone on to score 25 goals in all competitions.
Premier League trio Arsenal, Liverpool and Leicester have since sent scouts to monitor the 28-year-old, with the Foxes later lodging an £8m bid.
The club also just confirmed the signing of Croatian striker Andrej Kramaric but this has clearly not deterred them from chasing the Bundesliga hitman as well.
Okazaki has recently admitted it has always been his dream to play in England’s top flight: “I haven’t heard all the details personally and I am not overvaluing myself but obviously it is nice to get that kind of offer,” he said following Leicester’s bid.
“It has been a dream of mine since my youth to play in the Premier League and I have been watching the Premier League since I turned pro.
“I am not saying that the level is higher than the Bundesliga but the leagues have a different kind of quality and different culture.”
“It would be very interesting. I would view this as my last chance, wherever I go.
“I think there is more individual quality in the Premier League, while it is more about teamwork in the Bundesliga and I think that suits Japanese players more.”
By Phil Wellbrook