If you're looking for anime similar to Steins;Gate: Hiyoku Renri + Nyan² Crisis, you might like these titles.
Faris is on her way to a competition in Los Angeles and she's invited Okabe, Mayuri, and the rest of the Future Gadget Laboratory to accompany her. However, the gang quickly realizes their American vacation isn't all it's cracked up to be after they're forced to spend the night at a rickety old motel, and Okabe almost gets arrested at the airport! But not even these events can stop the mad scientist from discussing world lines and Kurisu's strange memories.
Ever since the great war of magic, angels have travelled from Heaven to the Earth to watch over the humans, to make sure they don't make the same mistake again. Lasty Farson (code name "Angel Rabbie") is Heaven's newest candidate for angelhood. Her mission: visit the people of Earth and help with their troubles! Unfortunately for Rabbie, her mission may be more difficult than she expected...
On a day like any other, Kakeru and Yuko chat on the school roof. But when things get a little heated, the pair – along with Yukiko, Takahisa and the rest of the gang – find themselves in another world once more... but this time it's pink! And the color of the sky isn't the only thing that's changed. Kakeru can now see through everyone's clothes (including Takahisa's, much to Kakeru's dismay); Tachibana can talk; and even Misuzu now wields an 'adult toy' instead of a sword. Just who is controlling this erotic new place?