Anyone notice that Hiro's return runs perfectly with where the show is story wise? He dissapeared from Kirby Plaza four months ago (during the entire "boom" incident). Yet, he returns four months later where the story of the show is running. I understand for story purposes, they couldn't have him return to Kirby Plaza that same night as we'd have to wait for a while for his story to catch up, but why did Hiro choose that time? Was it just...luck on his part? Did he stay in Japan for four months and decide that since he spent four months there, that he'd make up for the lost time by omitting the four months from the present?

Or he just has good time management.

He probably has the ability to go back to his direct timeline.... like his current life, if he stays gone he needs to reapear where he would be... like in the case of Charlie. He was gone from Ando for a while too.

Mostly it's just the only way the plot would work

But also, if he spent four months in Japan (which is possible), then he would naturally return to his own timeline four months after he left