When he had initially returned from the future he had decided not to meddle much with the future, as he knew that the butterfly effect was no joke.
He just wanted to build his strength while laying low! He would only start acting when it was truly necessary.
But things had happened way out of his predictions, as they got more and more complicated the more he tried to stay away from them.
Everything was so different from what he remembered, and what he expected it to be. So different that he couldn't understand if this truly was the past he had lived through.
In his previous future, he had spent all this time only on working and studying, and even when the systems day hit, he was still reluctant to use it.
It was only after the life-changing time with Yoshida Gina that he started wanting to get stronger, and more powerful.