The 26-year-old has still three years left on his four-year contract with the J-League outfit.
“We received an official letter from them,” explained Kobe team executive Masahiro Wada.
“We cannot say what will happen in the future, but I have to point out that Okubo has a contract remaining with our team.
“I suppose the German club realises that. We will hold discussions in the future.”
