In professional wrestling, Kobayashi has won several championships in his career: the GHC Junior Heavyweight Championship, which he held on three occasions, as well as being one half of the GHC Junior Heavyweight Tag Team Champions twice; once was the inaugural reign with longtime partner and rival, Naomichi Marufuji, which saw the two hold the title for almost two years, as well as a reign with protégé, Taiji Ishimori.
After starting his career in All Japan Pro Wrestling (AJPW), Kobayashi's home promotion is considered to be Noah, his destination following the departure of wrestlers from AJPW but due to Noah's involvement in the Global Professional Wrestling Alliance, a global organization of cooperative promotions that allow their competitors to travel abroad to other companies, he has wrestled extensively in previous years in American promotion Ring of Honor (ROH).
He initially wrestled under his real name, but due to potential confusion with his mentor, Kenta Kobashi (in both English and Japanese), he dropped his surname, only to use his given name, which he spells with Roman letters in all capitals.