Sensei Wraith (Ninja ドレスを着て悪趣味とのペンギンは、本当に本当に本当に本当に本当に本当に本当にいたずらペンギン。) is Sensei's brother, but evil. Sensei Wraith lives at the Dojo, but is rarely seen. His appearance differs from Sensei, with a purple coat and grey-blue wings. He has a Yin and Yang symbol on his hat (which might refer to Sensei as the Yang, Sensei Wraith as the Yin) and makes his debut as a boss in Mission 12: The Dojo Case. 影先生の秘密は、河を殺すのだ！