Nikolai Petrovic is mentioned in Tekken 7 as an associate of Kazuya Mishima whilst talking to Bruce Irvin Ganryu and Tetsuo[three asscioates of his 4 actually if you count Nikolai]He was a former member of spetsnaz who betrayed them and gave his services to Kazuya he is fluent in Russian Japanese Chechnyan and english.He also created Jack-7 for him.He also has a wife who was the former member of the now disbanded G corporation.He is also a mercenary who is revealed to have actually helped Kazuya killed Leo's mother