Zoeeboop's Favorite

Masaki started this story as an incubus. Incubi can't fall in love. When he fell in love with Shimuzu, he lost his position as an incubus and disappeared, but was reborn as a human. (God is generous in this story). When he is turned human, Masaki can't remember his past as an incubus like Shimuzu can as a fallen angel. Shimuzu remembers Masaki, he remembers his love for him, but he also remembers what he did to hurt him. This is why he pushes Masaki away at first. He doesn't want to hurt him again. Masaki misunderstands the rejection, thinking that Shimuzu did it because he misses the "other" Masaki. Shimuzu is also not entirely convinced that this person is his Masaki reborn. He still has love for him and wants to protect him, but he also wants some proof from this Masaki that the two Masaki's are the same soul. Then, Masaki makes it clear that he has no past memories before he met Shimuzu as his neighbor. Only with this proof is Shimuzu convinced that this Masaki and HIS Masaki are one and the same. When Shimuzu takes Masaki in his arms in the final frame, he has accepted that this Masaki is HIS Masaki.

At least, that is how I read and understood it.