The three boxes contain Pale Tones, which look like muted pastels, Vivid Tones which are the bright, vibrant shades and Deep Tones, which are your earthy colours. I love the pastels in particular as they are quite unusual colours.
The lead is wax based like Prismacolor but Irojiten are significantly harder than those. I'd say they're not as hard as Crayola but not at all soft and crumbly either, so I'd class them as a medium hardness. This makes them a lot more reliable when sharpening as the leads don't break easily, but I've found they don't hold a needle-fine point for more than a few seconds before the very tip of the lead snaps off. Anything less blunt than super sharp is fine though.
The hardness of the core does mean you have to work harder to get the maximum pigment out of the pencil, so make sure your comfortable using relatively hard pressure before buying these pencils.
Here's a picture I coloured with Irojiten (I used PanPastels for the moon background) from Dagdrommar by Hanna Karlzon. You can find a quick video of me colouring the hair here.