I'm astonished at how terribly bad Puzzle & Dragons: Super Mario Bros. Edition is doing. Sales are front-loaded as hell, surprising for a title like this.
[3DS] Puzzle & Dragons: Super Mario Bros. Edition <RPG> (GungHo Online Entertainment) {2015.04.29} (¥4.320) - 179.926 / NEW
[3DS] Puzzle & Dragons: Super Mario Bros. Edition <RPG> (GungHo Online Entertainment) {2015.04.29} (¥4.320) - 38.914 / 218.839 (-78%)
[3DS] Puzzle & Dragons: Super Mario Bros. Edition <RPG> (GungHo Online Entertainment) {2015.04.29} (¥4.320) - 13.844 / 232.683 (-64%)
It's basically hard mode DLC for Z which plays more like the mobile game, so I guess doing the grind again is not really appealing for people who are already high-level in either game. That doesn't explain the weak first week, though.