u/firebaron

Is there any currently running manga where the volume release has good bonus content? Like concept art, character and story detailed or answering questions like One Piece's SBS? Or exclusive bonus manga. I always get let down when I get a manga physically and there's just nothing between the chapters. I was hoping Ichi the Witch or Ultimate exorcist have something to justify buying them after already reading them online, feel free to include any Jump+ or manga+ series as long as they're out in English.