Can I charge my UK Nintendo DS in Japan?

Do I need some sort of adaptor, or is it just too dangerous to attempt it?

Also, does it take longer because there is a lower voltage?

you can charge it fine just you need to buy an adaptor to convert 220v to 110v
it is the same if you go to the US to and Canada

Do I need some sort of adaptor, or is it just too dangerous to attempt it?

Purchase a Japanese Charger for the DS, at any game store.
We did this with our Australian DS in Japan, and Australia has the same voltage (240 V) as UK.

Will I be able to charge my DS in Japan, without a problem?

Your Canadian version shouldn't have a problem, since it doesn't need a converter or anything, and uses two prongs like in Japan.

Thanks John.

i might bring my DS to japan and can i use my charger in japan?

i might bring my DS to japan and can i use my charger in japan?

It should be ok. I just checked my Japanese DS charging cord and it is region specific, i.e. it states that input is 100v 50-60hz. The difference is that the US is 110v which could possible cause the charging cord to heat up and cause a fire, although the chances are low. Just be careful and don't leave it charging for long periods especially if you will be absent.