Rather than an anthropomorphic book per se, this mighty fighter is a book manifesting a body with its countless pages. Straddled across his chest is a dense book with old, OLD writing on the cover (If you know Sumerian, you'd know it!). It serves as the primary 'anchorage' point for the rest of the pages making up the LLL's body.
Sprouting from the layers and layers of pages constituting his torso and abdomen are a quartet of arms, each as thick around as a two-liter bottle. Wrapped around his neck is an enlarged cloth bookmark, worn as a thin cape.
It's safe to say the rest of him is similarly constituted of pages with text constantly shifting over its form, but it's all clad in a luchador singlet, tights, and boots for ambulatory capacity. The LLL 'knows' how to walk, despite being capable of simply floating anywhere.
The LLL enjoys martial arts in almost every form. Its pages are loaded with damn near every conceivable type known on Earth, and now that it is mobile, it seeks challengers and worthy opponents with a startling zeal. Though, whether by its own merit or from simply knowing of the thousands of years of knowledge poured into it, the book does not attack in ways that would be considered 'dishonorable'.
The grimoire appears fond of communication in general; textual, oral, aural, and visual. Divulging information from it can be...difficult however, as it prefers to expound at length of great battles it has never seen and warriors it has never met.
And be mindful of its stride. IT TAKES LAAARGE STEPS!