BERLIN (AP) — German police say they rushed to an apartment in the southwestern town of Neustadt after receiving a call about suspected domestic abuse — only to barge in on a voluntary class on Japanese bondage.

Neustadt police said Thursday a concerned neighbor called to report that two men were abusing a half-naked woman in a nearby apartment. When police arrived they instead found the tenant, a teacher of Japanese Shibari, instructing a couple in the basics of erotic bondage.

In a statement headlined "Fifty Shades of Neustadt," police said "the couple was well and in a good mood" when they inquired about their situation Wednesday night.

They even offered to have the officers participate in the class, but the police politely declined.