Thanks for the chapter, intriguing mysteries. Though the story seems to be complete. Girl 1 found alien friend and then killed herself for some reason and so Girl 2 used a coin to have the power to become her and I guess as a bonus have the power to become reality itself. So Boy 1 got mad and strangled her like a fuccboi and then obtained the power to revive her and as a bonus be immortal. It seems that everyone secretly gets 2 powers but not sure how Shuichi so crazily applies that he needed his mind wiped along with the sister.
My best guess is the sister caused girl 1 to commit suicide.