This intriguing puzzle was designed by Vesa Timonen, who designed several cast puzzle by the way, with usually a common point: some twists involved.
The shape of the pieces is pretty strange and I feel it may be a nice idea for earings ;-)
Anyway you will have to make several steps to separate the pieces, many more than what should be required to solve a level 1 cast puzzle. Moreover, the steps are not that easy and the last one can be forgotten easily. Plus if you have a bit of friction between both pieces (unfortunately, even if Hanayama's puzzle are mass produced and are usually of good quality, you will likely not have a whole collection of perfectly made cast puzzles....unfortunately), then it may be difficult to guess some steps.
Not sure how Hanayama classifies the cast puzzles....obviously it goes with the wrong rating (too) often, even if it depends on one's skills.
Don't start with this puzzle if you intend to start from easy to difficult. A beginner will have a lot of difficulties.
Not my favourite among the level 1 cast puzzles, but still a nice one!