Also known as: 紅玉の書
A supporting character in Fate/Samurai Remnant. A sentient magical tome that floats in the air and speaks like a human. Miyamoto Iori (Fate) inherited him from his adoptive father. He is an ancient Western book who taught Iori magecraft and recognized Lancer's face upon first seeing her, though he initially couldn't place her identity.
He appears as a leather-bound book with two eyes and a mouth lined up vertically.
Character Design: Wataru Rei
Voice Actor: Chafurin