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