To get an understanding of why Bujinkan Ninjutsu is a good self-defence system it may help to define some of the types of martial arts that are out there. This is not to say that other martial arts are inferior, but it does help to understand what their focus is and why they may not be as useful in general self-defence.
Sports Martial Arts
These martial arts are systems that focus on competition such as Judo, taekwondo, wrestling or boxing. In order to manage the risks of injury to competitors there needs to be a set of rules in place. The martial arts then focus on teaching practitioners to most effectively work within the rules to the detriment of any techniques that fall outside or countering any attacks that are outside these.
Like other physically demanding sports, size, gender, age and experience can offer a significant advantage so we start to see combatants grouped in compositions accordingly, this then puts a high reliance on physical fitness and condition.
If you are a large man young man with a high level of physical fitness and don’t have any injuries and your component does not do anything outside the confines of your system, you will probably do very well. If you are facing a larger, stronger, fitter opponent your skill level will have to be disproportionately better than your opponent’s.
Some sports martial arts may be detrimental when dealing with multiple attackers they may encourage you to sacrifice manoeuvrability when trying to immobilise an opponent. Armed attackers could also prove to be an issue to sports martial artists as weapons are not permitted in most sports martial arts the ones that do allow them such as kendo are highly ritualised and very specific.
Modern Military Martial Arts
The modern military system as Krav Maga and Systema, were predominantly developed to teach soldiers how to deal with life-threatening situations when denied the use of their primary personal weapon, a gun. Modern military’s predomination relies on firearms and therefore this is where they focus soldiers’ training. None firearms combat training generally has to be taught in a relatively short period of time, as a result, the techniques tend to be simplistic and rely heavily on strength, aggression and speed.
These systems do not have the disadvantages of being confined by rule sets and will do much better when dealing with armed or multiple attacks. However, they do rely on physical strength and condition and use high levels of violence.
How is Bujinkan Different?
Self-defence situations are often ambiguous. The intentions of a potential attacker may not be initially obvious, they may not have a fixed idea about what is going to happen. They may be trying to work out if you are an appropriate victim. You are unlikely to know if they are armed or if other people may become involved. This is a problem for both sports and modern military martial arts using a specific level of violence that may not be appropriate for any given situation.
In the Bujinkan, we learn fundamental principles of combat that are not dependent on your physical size, strength or condition. Many practitioners train into their 80s are smaller, women and or have physical disabilities. The Bujinkan allows the practitioner to tailor the art to their limitations.
Bujinkan is a sophisticated martial art, and it can de-escalate a situation or use levels of violence that are appropriate to the situation without limiting your options as the situation progresses. This is important as it gives you options in a self-defence situation that maximise your options of achieving a less detrimental outcome for yourself and others. It also allows you to better deal with a situation in a lawful way.
Yossi Sheriff has a couple of YouTube videos that talk about the level of violence
If you are interested in the legal side of self-defence in the UK, I would recommend you look at the Crown Prosecution Service guidance.