Unicode usernames

Is this the case and can you provide an example, thanks!

Content-Type: Application/json; charset=utf-8
Accept: Application/json; charset=utf-8
Api-Key: f9c13aafa9b21baf778161bff66a62533ba650b6e4542e3e9788e98c55ded869
Api-Username: \xe9\xa3\x8e\xe4\xb9\x8b\xe6\x97\x85\xe4\xba\xba

Always prompt
You are not permitted to view the requested resource. The API username or key is invalid