Hayato Fūrinji, also commonly referred to as the "Elder", is one of the supporting characters of History's Strongest Disciple Kenichi. He is Miu's grandfather and the undefeated elder, head master, and strongest master of the Ryōzanpaku Dojo.
Hayato recalls that he took on 500 martial artists at once and was extremely reckless in his youth and violent to boot, to the point where he deliberately spilled tea over another relaxing fighter's head just to goad him into fighting. Unlike Kenichi, Hayato would take on anyone, man, woman, child, and even animals. To this date, Hayato still takes on anyone.
In his present, aged state, Hayato is a kind old man who has been wizened from his experiences. However, he still has a strong sense of justice, viewing those that fight for justice have great power and must have responsibility for that. It is this philosophy that may have motivated him into his travels over the years to protect the innocent and keep Miu from falling down the wrong path. He possesses a reckless streak and can also be very arrogant, the former of which is shown in his tendency to spend the dojo's money as well as getting carried away whenever he gets a chance to showcase his strength. He also tends to speak out his often over-simplified plans to others through even much more over-simplified and blunt manners of speech (e.g. "The fight until you're the last one standing plan", "The run and run and until they finally catch you plan" and "The giant dealing with it when it comes plan"). He's rather cocky in fights, such as overestimating himself and bragging about his numerous fights in the past, showing a bit of a boastful side on his part.
Hayato possesses a soft spot for Miu, stating that for anyone to ever marry her would have to first defeat him in battle. In fact, when he saw her kiss Kenichi on the cheek and he saw the whole thing, he was so angry that all the other masters had to hold him back from killing Kenichi. He even once threatened to kill a man who was holding her hostage despite being a devout follower of katsujin ken. He loves his granddaughter very much and worries over her well being when she's hurt or in danger, such as when she was going on the ski trip with her school, Hayato was worried about her panicking about how her mother died in the snow. He was also worried about telling her about her past with Saiga, wondering how she would react with how her father abandoned her and her dying mother. When Miu was taken by Jenazad, Hayato only blamed himself for this and became desperate in his search for her, such as traveling all over the globe in his search for her while angrily shouting out for Jenazads name. When Miu was safe he became mad at Kenichi for holding Miu in his arms then became very happy that she was safe with tears of joy that Kenichi had protected her.
He is also quite fond of Kenichi Shirahama, calling him "Ken-chan" and is the only one who apologizes to him for the Hell that he and the others put him through (despite, as Kenichi puts it, simultaneously holding the rank of the most brutal training), however, this is implied as apparent mainly because he truly enjoys tormenting the boy. Even though he apologizes for the Hell he's put through, Hayato also has put him through similar brutal training, such as when he took him on more than one training trip, Kenichi noted how horrifying and tough it was to just survive the training. He has even giving Kenichi his approval to date Miu, his granddaughter, for winning the D of D tournament (should Miu agree to it). He tends to not let Kenichi get too close to Miu, such as reminding him if he wants to marry her, he must defeat him (though this was also due to him having caught Miu kissing him on the cheek, greatly angering Hayato). After Kenichi saved Miu from Jenazad's grip, Hayato placed his hands on his shoulders and tearfully thanked the boy for saving his granddaughter, showing that Hayato knows Kenichi can protect Miu. Also, he is not above scolding Kenichi should he do something reckless, such as fighting a master class fighter and as a result putting Kenichi under house arrest. However, in truth, Hayato and all the other masters were very proud of Kenichi of fighting a master class opponent and for fighting for his friends. He also states that Kenichi reminds him of when he was younger and respects Kenichi for that. Others who know the Elder, such as Silcardo Jenazad, have also noted the similarity between the two.
Hayato has a disguise he uses to (rather poorly) dress in called Garyu X. He only wears a mask with a robotic design to look like a 20-year old disciple and even believes the disguise to be perfect despite his outfit still being the same. However, everyone (except Apachai) know it's him and all believe that he's finally starting to show signs of insanity due to his age.
Hayato is a very tall and fair-skinned man with blue-eyes and blond hair. He also sports a chest-length beard, mancho mustache, and reaching mid-back with a few strands of hair to form a thick antenna-like strand hanging in front of his face. Despite his advanced age, he has largely muscular and well-defined built, few wrinkles, and not a single gray hair. In the past, his hair was shorter and he did not have a beard and donned similar battle gear as he does in the present. When he was fighting Yami with Kushinada Mikumo, he wore the robe he is commonly seen in and grew his hair longer.
As Garyū X, Hayato dons an under-sized mask and a Kamen rider belt, using this thin guise to pose as a 20 year-old disciple.
Not much is known about Hayato's past but it has been shown in flashbacks that he took on 500 martial artists at once. He also at some point had a son, Saiga, who sired his granddaughter Miu, whom he gained custody over after the death of her mother. He arrived too late too see what had happened, but found his daughter-in-law dead and his granddaughter hidden in the snow. During WWII or the Cold War, he worked with Mikumo Kushinada to defeat many Yami bases.
It has also been shown that Hayato used to travel the world with Miu and help out people in need where he would also instruct her in martial arts, around the time of which he met Apachai. When he met Apachai, he fought him on a cruise ship due to the latter being tricked into thinking he was helping the victims. Miu was also on the ship and held as hostage, greatly angering Hayato. After telling Apachai of the meaning of the children held hostage, Apachai turned sides and assisted Hayato in saving them and his granddaughter. Afterwards, Apachai choose to follow Hayato and the former brought him to Ryozanpaku due to seeing good in the man.
At some point, Hayato became acquainted with Silkwat Junazard, a member of Yami. For a time, they were friends and Junazard taught Hayato much of his land's medical techniques. Later, Junazard and Hayato would end up fighting each other, with Hayato stating that Junazard gave him a hard time. Before a clear winner could be determined, the battle was called off by the Elder who was forced to leave due to his boat fixing to leave soon.
He became acuanted with the master of the Tenchi Mushin Ryuu schools master Kai Midou, having been aware of Ogata's experimentation he did on him, leaving him with bad health. He was also responsible for meeting his lone disciple, Tsutomu Tanaka and helping him marrying his only daughter Mayu Tanaka. However, the elder was unable to see that Ogata would later take not just Midou's life, but also Mayu's and her unborn childs life, leaving Tanaka a broken man, to which the elder would be the only one with the knowledge of the incident.
Hayato is regarded as a man of no equal and was even nicknamed "The Invincible Superman" to shelter this fact. He is quite possibly the strongest martial artist in the world and is capable of many feats that are considered beyond human potential. He is noted to even at 0.0002% his strength while closing his eyes and splitting his attention two ways, he is still ranks among the mightiest of fighters. He is also the master of the Ryonzanpaku Dojo which is said to be the strongest masters in the world. His skills are regarded as a class above even Grand Master individuals as a Legendary Master.
- Master Healer: While not his specialty, Hayato is skilled and otherwise knowledgeable in a variety of healing arts. He is even able to use his Ki to heal people.
- Anatomy Manipulation: Hayato's control over his entire being is so great, he can freely use various parts of his anatomy in seemingly inhuman ways. Several of these abilities are among his 108 techniques.
- Power Suppression: Hayato, being a man that values life, is able to subconsciously limit how much of his physical might he can actually use, even up to only 0.0001% of his full power. However, in doing so while battling, it also proportionately reduces the level of his compassion towards others.
- Immense Strength: In his younger days, the Elder was so strong that it is revealed that he took on 500 Shaolin masters at once. Even though the Elder is much older, he can throw people like shuriken, throw a bomb as large as himself several feet into the air, bend a battleship cannon, knife strike through a tree and rip it in half with ease, slice thick branches from trees using only two fingers, and even turn over entire tanks. Even with his eye's closed, Akisame states that he is still the most powerful man alive. Also, despite his advanced age, he has shown remarkable stamina, having yet to show any signs of fatigue from prolonged fights, even fights lasting as long as a week with little nourishment's, or his various inhuman feats like running across sea water.
- Immense Speed: Despite his large size and built, Hayato Furinji possesses speed so fast that he is able to run on the water like the wind, shown when rescuing Kenichi's sister, Honoka from the sharks. In the D of D tournament, shown in his fight there, when fighting Muay Thai Taifun team's Gaien Osugi, Hayato Furinji is shown to perform low kicks at an incredible speed, resulting in Osugi stumbling and wondering why he tripped while the Elder merely stood there. When his movements are captured on the high-speed camera and played back, despite the Elder's moves being slowed to 1/1000 of a second, only a blur where his right foot was supposed to be was seen.
- Hybrid Martial Arts Master: Due to his years of experience, he has advanced knowledge of various styles and can copy any move of a master-class fighter, no matter how unique it is to the opponent. It is revealed later that Hayato Furinji had created his own 108 personal techniques.