He is also well known for his tenure in American promotion WWE where he worked under the name Hideo Itami in the company's developmental territory NXT and later in their cruiserweight exclusive brand 205 Live. A former amateur kickboxer, Kobayashi's wrestling style is based upon strong kicks and strikes. Kobayashi started his career in All Japan Pro Wrestling (AJPW), before moving to Pro Wrestling Noah; through Noah's involvement in the Global Professional Wrestling Alliance (GPWA), a global organization of cooperative promotions that allow their competitors to travel abroad to other companies, he has wrestled extensively in American promotion Ring of Honor (ROH).