Kimagure Orange☆Road, Steins;Gate Movie: Fuka Ryouiki no Déjà vu Recommendations
Steins;Gate: Fuka Ryouiki no Déjà vu appears to have been influenced by Kimagure Orange Road in various ways. They both use some similar time-travel plot elements, as well as alluding to parallel universes and having a sort-of-tsundere female lead.
The last few episodes of Kimagure in particular has a similar plot:
*SPOILER* The protagonist's time-travel to the past causes ripple effects in the future which he needs to fix, and along the way he meets a younger version of someone he knows. */SPOILER*
The Disappearance of Haruhi Suzumiya was also influenced by Kimagure Orange Road, which explains some of the similarities between the Haruhi Suzumiya and Steins Gate
"the first kiss"...
If you haven't watched Kimagure Orange Road yet, but love Steins; Gate: The Movie, it's time to watch where that "first kiss"of Rintaro Okabe comes from.