Yurison

Not too far in the future, a cheerful yet slightly shy high school girl named Tenma Ushio receives a message from a mysterious stranger named “Hitoha” that simply said, “I love you.” Though surprised by the first confession she's ever received, Tenma decides to meet the message-sender to decline the offer in person. When she heads off to the arranged meeting place, little does she know that this marks the beginning of a world-shaking event. Girl meets...? A love story unlike any other is about to begin!

(Source: Comic Ogyaaa!!, translated)