The CSKA Moscow star was in inspired form as he guided Takeshi Okada's men past Denmark in their final Group E game on Thursday.
Japan finished runners-up after the 3-1 win and as a result qualified for the Round of 16 where they will face Group F winners Paraguay.
And the 24-year-old, who scored the first and set up the third against the Danes, revealed he was not as pleased as he thought he would have been following the win.
"I'm not happy and I don't know why," admitted Honda.
"Before the start of the match, I could recognise the importance of the match and had expected to be really jubilant if we won.
"For Japan it's a big win. I'm glad we won but I am not satisfied.
"The next game is more important. I want to show the Japanese that nothing is impossible.
"We have to still go further and step by step we have to go about doing this.
"There will be challenges, but I believe the team as a whole can succeed here."