I found Japan to be a great place, and I would think, a safe one for kids.
There are problems though. Every country has them. No drugs, as noted, very restrictive on firearms, weird regulations on porn but if you are a straight arrow that doesn't screw around you'll be fine. Stay clean, stay away from the Yakuza and everything is okay.

Cannibis seed is in the Shichimi Togarashi spice. I suppose if you were really a fiend, you could grow some, and mix it in your brownies. Don't smoke it though, police would be on you quicker than you can exhale.