Asano joins Hannover on a season's loan, having spent the past campaign with VfB Stuttgart.
The forward said, "I am very happy to come to Hannover. I'm going to go full throttle to repay the club's confidence in me and make the 96 fans happy."
Hannover chief André Breitenreiter also remarked: "Takuma is a versatile attacker. He brings a lot of speed and speed of action on the pitch - at the same time he displays a strong mentality.
"We are convinced that he has great potential and will develop further at Hannover 96 and take his next step."