Tarn, also translated as Tarn, is a character in Transformers IDW comics and the captain of the Black Dog Team (DJD). At the same time, Lake Xuan Ji is also the place name of Cybertron.

Xuan Ji Lake/Tarn, head of the Decepticon Justice Department (referred to as DJD/ Black Dogs). Like transfiguration (always switching between human form and vehicle form), music, classical literature lovers. The main duty of the black dog team he led was to clean the deserters and traitors of the Decepticons, and the means were extremely cruel.