Hitler didn’t tell the Japanese about his plans to attack the USSR, so the Japanese committed to going south into Indochina, Indonesia, and the Philippines. If Hitler had clued them in with his plan there might have been no Pearl Harbor. Or maybe not: FDR cut off their oil, and they weren’t going to get that in Siberia.
Japan was already upset with Hitler, after he signed the Non-Aggression Pact with Stalin, despite the Anti-Comintern Pact.
Then Zhukov and Company whips Japan at the Battle of Khalkhin Gol in 1939, and from that point on, Japan turned its attention south.