Post anime about cellphones.
A girl falls in love with a girl.
Unable to confess, she is gifted with by a deus ex machina with the girl's phone address. Never minding the laws of the Taisha, she immediately calls her, and is overjoyed to find out that she has been summoned to her, along with a friend as well.
But, on that same day, when she recounts their previous adventures to the girl, she only looks at her with a perplexed expression. After some investigation, she finds out that the girl she called is not the same girl she fell in love with. In fact, she doesn't exist in this god-tree world at all. She is the girl's post amnesia counterpart, who has fallen in love with the MC of the show, who too is blissfully unaware of her crush.
Hijinks ensue as the two strike up a deal and she shares the Taisha’s darkest, most private secrets in order to equip the other with the weapons they need to destroy the tree. While the two chase their respective loved ones, DRAMA ensues as the girl starts to remember her instead and question the NATURE of YUUSHA.
You mean Keit-Ai episode 12?
>Unable to confess, he talks to his AU self only to end up sacrificing himself, the end
Also has best yandere of all time