Japan has won four Asian Cup titles in the past six editions and is seeking a record fifth continental crown in Australia.
The Japanese needed only eight minutes to score its first goal as Endo's long-range strike beat Palestine captain and goalkeeper Ramzi Saleh's dive.
"Endo's early goal was great," said Okazaki, who was named man of the match. "It gave the team great momentum. We played well, however, we could have been better.
"We are not satisfied with four goals we should have scored more."
The Palestinians sat deep in defense to negate Japan's intricate passing and movement but had no answer for Takashi Inui's strong run and cross that found Kagawa, who sent a shot from the edge of the box. Okazaki stooped low with his head to deflect the ball past Saleh in the 25th minute.
It wasn't until the 40th minute that the Palestinians managed a scoring chance with Ismail Alamour's shot sliding wide of Eiji Kawashima's goal.
The defending champions scored their third when Honda stroked home a penalty after Musab Battat pushed Inui in the box in the 44th minute.
Yoshida scored from a powerful header from Kagawa's cross just after halftime as Japan tried to put last year's disappointing world cup showing behind it.
"The most important thing we achieved today was the confidence we achieved," Okazaki said. "And also to gain back the confidence from the poor result from the World Cup campaign."
The best chance for the Palestinians came in the 81st but Abdallatif Albahdari sent his strong header narrowly wide.
"People may think Japan was superior over Palestine but it was not an easy game today," Aguirre said. "They've played against China and Uzbekistan and they drew with China and Uzbekistan to score only one goal against them."
Despite the lack of chances, a small contingent of Palestinian fans in the crowd of 15,497 waved flags, beat drums and sang for the duration of the match.
"The feeling has touched our emotions, Palestine coach Ahmad Alhasan said. "To see the Palestinian people everywhere in the world can be gathered to support Palestine.
"This is the only national team that plays in this tournament that is still under occupation."