After the unexpected end of the battle between Alma and Kanda things started to get weird and confusing for Allen. Kanda and Alma is acting really weird around him and it's annoying him to no end that he can't figure out why.
Prior to their three years of relationship, things running smoothly between them until one day,Allen began to change so does Kanda. This change threatens to break them apart and their relationship. But is there a hidden reason behind Allen's change of behavior? Inspired from the song of Mai Hoshimura entitled 'REGRET'(D.Gray-man 7th ending theme song).