Omoto Ryu Jujitsu has two ways of practicing techniques, well three if we include Shiai or Randori but, I will get to that later on.
Nagare means flow or current, it is a free form exercise where students flow between elemental strategies and styles of fighting. It is not limited to grappling or striking it is a an exercise in give and take. The Uke attacks and the Tori defends, ultimately "winning" the exchange. The Tori then becomes the uke and attacks with the former uke becoming the Tori.
This allows a practicers to apply the cycle of the five elements to attack and defense. For example, Bob attacks by using the Wood or Void strategy of feinting a punch to the face, Kata Tsuki as uke. Bill counters by using the Metal or Air strategy by stepping back to avoid the strike as Tori and delivering a low stop kick to Bob's knee. Bob now acting as Tori, with Bill as the uke, uses the Earth strategy of defense by taking up a fighting stance and waiting for Bill to attack. Bill moves forward to enter striking range and Bob responds with an Ashi Tai Tsuki as a step hit, meeting the threat head on as per Earth strategy. Bill then assuming the role of Tori counters by executing a Judan Uke into a Ura Ippon Nage, applying the water strategy. Bob, likewise applies the Water strategy reversing the Ura Ippon Nage into a Ude Gatame... And on and on it goes.
Nagare os always about flowing from one technique and tactic to the next. Nagare is also characterized by drills like Nagate-Te or flowing hands. Flowing hands is similar to the trapping found Jeet Kune Do or Wing Chun. Nagare- Te has three particular drills, drill one uses the back of the hand or forearm to practice redirecting an opponent's energy (this is done to in an "Aikido like" way) from the blocking motion, the second drill is similar to sticky hands in Wing Chun where one person (the Uke) practices striking at vital targets while another (Tori) practices blocking and redirecting the uke's strikes and the third drill aims as including joint locks and throws from the first two drills.
This is very similar but still different than the Kata practiced in Jujitsu. Kata refers to the application of techniques against a none resisting opponent. This can some times and especially at higher levels of training where strikes to vital areas are included with the application of various techniques. The Kata for many throws and joint locks does involve opening strikes to injure and open up the opponent for such grappling techniques, as well as strikes to vital areas to end the encounter once the joint lock os executed.
Now I have to stress something, classical jujitsu joint locks are not locks but breaks. They are intended to be executed with explosive power and dealing pain or injury from an opening strike, followed by a disabling break or joint destruction and ending with a follow up strike to a vital area that is intended to Kill, Cripple or Maim an enemy in battle.
This is only half of the conditioning of the mind and reflexes of the student. Because this brings up the third form of conditioning and practicing techniques. This third, form Shiai (contest) or Randori (sparring) is the application of techniques against a resisting opponent. Shiai means contest and it is the old term that duels were fought under. Shiai were little more then "street fights" without many, if any, rules. The term Randori comes from Judo to name competition fighting events with rules and limited application of techniques. This made competition safer and allowed students of judo to gain a much higher level of experience using their art without fear or risk of injury...
Omoto Ryu Jujitsu has likewise, adopted this type of free sparring. In addition Omoto Ryu also uses a series of Randori drills. Theae drills include sparring multiple opponents, as well as, other psychological conditioning drills used to strengthen the mind as well as the body.
This sets the stage for something I need to address about facing more then one opponent in a self-defense situation. There is a fallacy in martial arts that because many traditional systems are designed to face multiple opponents they are able to do so. This is a problem in thinking. These arts were designed for use on the battlefield and so in facing multiple opponents (which was a strong possibility) they do have training included in the traditional systems.
The thing is a master level fighter maybe able to defeat multiple opponents of lesser skill and ability, however not all of one's opponents will be of lesser skill and ability. This goes into the self-defense fantasy that all criminals are stupid, lazy and have no training or that one's own training some how gives one a greater advantage then the "average person" while martial arts often sell the fantasy of being an "elite fighter" to sell classes they often don't produce the level of skill they advertise and don't make a martial artist an "unstoppable killing machine" like you see in Hollywood movies.
In the real world if you are fighting one person, you will likely get hit & if you are fighting multiple people you definitely will get hit. Sparring multiple opponents, as well as the kata or nagare of such, may not make you the Hollywood martial arts killing machine but it will give you tactics and teach you what works and what doesn't. It will also teach you to take a punch and to understand the chaos of facing multiple people at once. Simply because it teaches you tactics and techniques does mean the art can promise success. That comes with one thing no art can teach, heart...