The Blues almost managed a remarkable comeback in the final in Tokyo, with INAC having been 3-0 up and cruising with 10 minutes remaining.
Recent recruit Rachel Williams gave Chelsea hope with a goal and then set up Hannah Blundell for a second, but they were caught on the break in injury-time and went down to the tournament favourites.
Williams and fellow England international Laura Bassett are the two high-profile additions to Hayes' squad so far and she is hopeful of adding more ahead of what will be a tough Women's Super League campaign judged on the recruitment drives being undertaken by some of their likely rivals.
"We have big expectations for next season at Chelsea and I think once everyone sees the signings we bring in you will see that we have very serious intentions to compete and win our league next season," Hayes said.
"I think once we complete the signings of a few more players we will add good quality to the team. But we also have some good youngsters coming through and I think you will see a much more competitive Chelsea next season.
"Being here has allowed us to build a spirit, which is the most important thing.
"We will have more time to train when we are back in England and we will use this trip as a motivation for the players as it has been a massive success on and off the pitch as we have had time to spend in the community in Tokyo and Okayama."
On Sunday's performance, she added: "We knew it would be a difficult game against a top team and due to the time of the year we didn't have the fitness levels to play a high-pressing game.
"In general I think we had good opportunities, we hit the bar and had a one on one but we missed those chances at crucial times and as we didn't convert 3-0 was too difficult a score to come back from.
"But the team showed great character second half and I think if we played them again during our season we would give them an even better game.
"INAC are a team that have played together for a long time and that is the difference. We have similar philosophies and they have top players but the time together was the main difference."