Hanayama Puzzle: Key

"Two keys linked together in such a way as to seem permanently joined. No matter how you look at it, there seems to be no possible way to separate them - or so everyone thinks. The keys are by all means separable. This is just one of the famous puzzles that has enjoyed popularity ever since its creation during the 19th century British puzzle craze. The key word is 'engage.'"

-Nob Yoshigahara, 1983

Difficulty 2 stars