In. If you draw a plane vertically from the outside edge of the line, and any part of the ball intersects that plane, the ball is still in play. Only when it completely crosses the plane is it out.
Tanaka, who scored the goal, and Mitoma, who lifted the ball just short of the line, have been childhood friends since elementary and junior high school.
Maybe it was a trick he was able to pull off because he was a trusted friend.