They can be. For those who are passionate about classic novels, wearing a t - shirt with their favorite book on it is like wearing a badge of honor. It also serves as a conversation starter. However, their popularity might not be as widespread as more mainstream fashion items, but within the literary community, they are definitely well - liked.
It depends. If you have the legal rights or a license to use the characters, then it's okay. But without proper authorization, it could lead to copyright infringement.
Sure, you can use manga for t-shirts. Just make sure you have the proper licenses or you could get into trouble with copyright laws. Also, think about how well the chosen manga image will look on the shirt and if it'll appeal to your target audience.
The book is definitely fiction. It weaves an imaginative tale that is not based on real events or people. The author crafted a fictional world to engage and entertain readers.