Epic Seven Character Artworks
The person behind the Youtube channel StepPLAY is shown above flipping through an exclusive artbook titled 'Epic7 Character Artworks First Edition'. Judging by the comments, this book is not for commercial sale and was possibly an exclusive prize given to the uploader for attending an event.
In any case, it's an invaluable resource for cosplayers and fanartists alike-- seen in the video are numerous outfit details and even characters who don't exist.
E7 Festa teaser video
The above video was shown at the Epic Seven Festa in June 2019. Preview artwork of Seaside Bellona, Aloof Lifeguard Sez, Furious, Vivian, Desert Jewel Basar, Apocalypse Ravi, and Cerise can be seen here.
Below is a collection of images from the credits that play at the end of the game. These are likely doodles and other fun creations made by the dev team and artists working on the game, mainly of Aither, Ras, Mercedes, and other members of the main cast.