u/RevolutionaryPen251

i got this hardcover version of the second book which surprised me because i didn't know hardcover versions of the original solid cover books existed. the isbn on wikipedia and other sources for the hardcover book are all the one with mikuru on the cover. this has a completely different isbn and no database i searched can identify it. photo 1 has hardcover on the left and paperback on the right just for comparison. i am just wondering why there is no trace of this version of the hardcover existing.