Manchester City defender Ko Itakura could sign permanently with Schalke.
The Japan international is currently on-loan at S04, where management are already discussing keeping him long-term.
S04 sports chief Rouven Schröder stated: "We will reconsider everything in our power. But we are not a rich club, a fee cannot be too much.
“He really arrived very quickly, identified with the location from the start and absorbed everything, a great professional.
"We definitely have the emotional aspect of this player on our side."