Wildcard Hijikata, ranked 169th in the world, went toe to toe with Tsitsipas in the early exchanges and looked capable of making it a contest for the Rod Laver Arena crowd.
But Tsitsipas, a semi-finalist last year, seized control when he broke serve in the sixth game and used his superior firepower to great effect as he raced away to victory.
Hijikata managed to stem a seven-game losing streak at the start of the third but never looked like producing the day's second shock after reigning champion Rafa Nadal (36) was earlier knocked out by American Mackenzie McDonald (27).
"Felt good out there, the ball was coming off the racket really well," Tsitsipas, who could become world number one if he claims his first Grand Slam title by winning the Australian Open, said on court.
"I enjoyed myself tonight."
"Whenever I'm back here it feels like home," he added of playing in a city with a large Greek diaspora.
In round three he will face a Dutch opponent, either 32nd seed Botic van de Zandschulp (27) or Tallon Griekspoor (26).
