Shifou

Shifou trains the paper-folding hole problem — one of the most demanding spatial reasoning tasks on aptitude and cognitive-ability tests worldwide. Watch each fold animate step by step, then commit your prediction on an empty grid before a single crease opens. Only after you lock in does the paper unfold over your marks, revealing the exact fold where your mental model broke and why. Five progressive families take you from single folds and doubled holes all the way to diagonal creases, off-centre folds, and reverse challenges where you see the final hole pattern and must work out the folds. Each family is a structured course built on 90 hand-designed items. Every correct answer is computed live from the fold algebra — nothing is stored, nothing can be peeked. The Workshop lets you author your own sheets: drag any crease, punch up to six holes, then watch Shifou solve your creation. The Planner works in reverse — paint the hole pattern you want and receive a fold-and-punch recipe. Cut and Open swaps holes for cuts, detects when a snip would split the sheet apart, and reports the symmetry order of the opened result. A built-in review queue groups past mistakes by cause — wrong mirror, missed doubling, on-crease hole, lost diagonal — and schedules them back on a spaced-repetition ladder so you fix the root problem, not just the item. No account required, no ads, no in-app purchases, and fully offline.