Apparently she is date_masamune although it hasn't been revealed yet in the anime. How would that work tag-wise? The current tag for her is bontenmaru_(oda_nobuna_no_yabou).
Book of Revelation黙示録 (Mokushiroku) - this is probably referring to the last book of the New Testament. However, the last kanji appears to be written differently, so I might be mistaken.
