If you want to train at our dojo you must be at least 16 years old.  

We decided so due to our experience. The reason is, that we expect a minimum level of maturity, seriousness, discipline  and personal responsibility - which is if at all - given at the age of 16 - most of the time even later.

In many Bujinkan Dojos the minimum age is 18 with some exceptions. We don't like exceptions so we lowered the age to 16.