|Hieronymus of the Holy Pen|
Hieronymus of the Holy Pen (聖筆のヒエロニムス Seihitsu no Hieronimusu) is a sub character in Shiori After Story. He is the librarian of Index's underground library whose authority is only below the pope Johanna. He has been living for at least a few centuries, but still likes milk and cookies, a hobby which others (Johanna and Shiori) commented as 'never changes'.
Hieronymus has made a rule that his face must not be seen, which is why Shiori Momono, who lives inside the library has never seen his face before. On the other hand, Johanna seems to be the only person whom he would show his face to, according to scenes where he is seen talking with her about her philosophy on parallel worlds. He also seems knowing Johanna's actual phenomenon state.
- Hieronymus could be possibly Eusebius Sophronius Hieronymus or Holy Jerome, a translator of the Bible.