Yes, it is quite popular. It has an interesting concept of a magician who 'eats' books to gain knowledge and power. This unique idea attracts a lot of readers who are into fantasy and magic - related light novels.
The 'book eating magician novel' could potentially center around a magician in a fantastical world. Maybe the act of 'eating books' is a metaphor for absorbing knowledge in a very unique and magical way. For example, the magician could use the knowledge from the 'eaten' books to perform extraordinary spells or solve complex problems in the story. It could also be about how this strange ability sets the magician apart from others in their world, leading to various adventures and challenges.
As I'm not familiar with the 'book eating magician novel', I can only guess. The title implies that the book - eating magician is a main character. There could be a sidekick, like a fellow magician or a non - magical friend who accompanies the main character on their adventures. There might also be a powerful wizard or a magical creature that plays a significant role in the story, either as an ally or an enemy to the book - eating magician.
It's hard to say exactly, but it could potentially explore themes like the power of imagination, the subconscious, or even have a battle between good and evil within the realm of dreams. Maybe the magician has to solve problems or overcome challenges in this unique setting.