NOTE: This article contains spoilers! Read with caution.
|金剛先生 / Kongo-Sensei|
|First appearance||Volume 1, Chapter 1|
|Nickname||Sensei / 先生|
|Family||The other gems|
|Occupation||Teacher and protector of the Gems|
Father figure for the Gems
Kongo-sensei (金剛先生, Kongō-sensei, Literally meaning "Adamant Teacher") is the head of the Gems, acting as the teacher, protector, and father figure. He teaches the Gems about the current world and its history, and decides the role suited for each of them. He has overwhelming offensive power and can disperse the Lunarians in one blow. He becomes incredibly intimidating when angered.
Every time the Lunarians appear, one Gem from a pair of patrol will ring their school's bell. He and some (or all) of the Gems will go to the scene and disperse the Lunarians. Unlike the younger Gems, he can stay awake for a long time and doesn't require sleep, although he still rests during meditation periods, implying exhaustion. When angry, he can crack an entire building and his voice is able to shatter the weaker Gems in close range. Later, it's shown that he disperses the Lunarians by cracking his arm and using very tiny fragments of himself to attack them.
Kongo-sensei takes form of a bald, adult masculine man wearing a Buddhist monk kimono and robes. He always wears a pair of white gloves and usually sports a black cloak when going outside. He is often shown with a somber expression, frowning with his eyes closed.
He might be like the other Gems, who are covered in a white powder that imitates skin. If so, it is unknown what his true color is underneath the white powder. The volume 9 omake discusses this, where the younger Earth Gems ask what color he really is. He explains that while he cannot give out full details, he confirms that he does have some transparency. He's described as solid and heavy, as he is able to create trembles with his footsteps and crack pillars simply by dropping his head onto them when sleepy.
Normally, he is very quiet and stoic. When he speaks, he is straightforward and concise. He only rarely displays emotions, but this is rumored to be because he is deliberately hiding them and that his face would be very easy to read otherwise. On the rare occasions where he shows humor, he is still as deadpan as ever.
His composure usually only falters under two conditions: first, when Gems put themselves in harm's way carelessly, second, when he is confronted by matters from his past, such as the subject of humans. These cause him great alarm. When he is angered, he is capable of tremendous unintentional destruction, shattering weak Gems with the force of his voice alone or cracking stone floors by walking over them. These emotional expressions never last long and he very quickly reverts to his relatively expressionless face.
Otherwise, he is nonchalant and tolerant. He allows Gems without critical duties to do work on their own times, and is blasé about them prying into his past or secrets.
Kongo-sensei seems cautious using his power as to not shatter the Gems, unless he decides to scold them for making trouble or putting themselves in danger.
He cares for the Gems considerably and blames himself when they are injured or taken away by the Lunarians. Kind and wise, he becomes sad when the younger Gems are sad. He only rarely demonstrates physical affection, such as hugging Antarcticite or patting other Gems on the head. For unknown reasons, he didn't tell the younger Gems about 'humans' and avoids any mentioning of them, instead vaguely referring to humans as an 'ancient species'.
He does not appear to sleep often, but his wakefulness takes a toll on him. He has a set period in a day where he goes under deep sleep-like meditation and becomes virtually impossible to wake. According to Jade, waking up sensei from this "nap" period is more of a struggle than fighting the Lunarians, as demonstrated by the Gem shouting and even smacking at their sensei in a futile attempt to wake him. Despite that, it is implied that he can be awakened from this state, as he once chastised the Gems for not doing so when the school was attacked by the Lunarians. During that same incident, he had drifted from meditation into sleep and starting dreaming, something which he considered reckless upon waking.
He is hinted to be very lonely.
- The great and terrible Sensei.
- The great and terrible Sensei. Rumor has it that the constantly furrowed brow is an attempt to hide the emotions that show themselves surprisingly easily.
- The great and terrible Sensei. But falls asleep all the time. Somewhat suspicious.
- The great and terrible Sensei. Extremely suspicious. Surprisingly bad at dodging questions.
- Shrouded in mystery. You won't discover the important details that easily!
- Enjoys meditation (otherwise known as napping). For many reasons, the Sensei is just always sleepy.
- The ever-sleepy Sensei. Apparently has no control over this.
- Kongo-sensei's history prior the 6th meteor fall is unknown at the beginning. Since he knew about it and the humans, it can be safely assumed that he was already alive when the humans existed. Chapter 64 reveals that he had been around long before the other Gems were born.
- Thousands of years before the start of the series, he had witnessed the "birth" of very first Gem at the Shore of Nascency, Red Diamond. Their, Kongo-sensei, recognising them as a life-form similar to him, became their caretaker, and carved out their rough edges, smoothing them out to be more human-like, and gave them eyes for them to see. He then clothed them and began educating the newborn Gem. Sometime after, they discovered a newer, but weaker, Fluorite. At Red Diamond's request to help the weaker gem, Kongo-sensei then constructed the School.
- Between Fluorite's introduction and the start of the manga, new Gems had been born, each of them being taken in, educated and given a jobs by Kongo. These ranged from as fighting, crafting, textiles, or strategy. Over the centuries, several Gems had been abducted and taken to the Moon by the Lunarians. 300 years before the start of the series, the new Gem had been born, Phosphophyllite.
- Phos was a special case compared to the other Gems. Kongo-sensei tried giving them different roles, such as medicine, strategy, industrial work, textiles and weapon forging, but they proved incredibly clumsy and inept at various areas. Fighting was out of the question, as Phos was born particularly fragile, having a hardness of 3.5, making them unsuited for combat. For three centuries, this left Kongo at a loss in trying to decide what job was best suited for Phos.
- He gave Phosphophyllite the job of making a natural history encyclopedia.
- He undergoes one of his "meditation" periods, during which two Lunarian sunspots appear, one of which attacks the school directly. The Lunarians release the slug Ventricosus onto the school. After pacifying the slug, Phos introduced it to Kongo-sensei and he welcomed her. He asks Phos to accompany the slug as part of their role's work.
- Phos asked him about Cinnabar's sadness and wasted potential on night duty, but Kongo-sensei apologizes to Phos and asks for forgiveness as he's still hadn't yet found a solution for Cinnabar and blames himself for the situation.
- He became angry when Phos disobeyed him by going to the sea and ending up coming back without their legs. He relieved Phos of their first job as the composer of the natural history encyclopedia since it put Phos in constant danger and caused more trouble than it was worth.
- When he asked Phos for a report about their experience under the sea, Phos mentioned "humans", causing Kongo-sensei to become alarmed and smash a table.
- After Phos gained new legs, he assigned them to Amethyst, who patrols a spot where it's common for the Lunarians to come.
- Because Phos was unable to sleep, he agreed to let Phos team up with Antarcticite. Later he told Antarc to go to Shore of Nascency after Phos lost their arms, which leads to Antarc's abduction. He was trapped by the Lunarians in front of the school. Kongo-sensei then guided and became Phos's teammate until winter was over.
- He slept for a while and woke up to find "Shiro" inside the school. He asked "Shiro" about its arm and lied when Phos asked him whether he knew the creature. Phos then asked if the dispersed "Shiro" is returning to the moon, but he said that it seems already satisfied.
- Kongo-sensei agreed to let Phos join him to fight the Lunarians. Phos was surprised when Ghost Quartz suddenly joined them.
- Kongo-sensei is a prayer machine built by humans in the past in order to pray for the souls of the dead in order to purify them. At some point prior to the story, his internal components became damaged and he consequently stopped purifying the souls of humans (The Lunarians).
- Kongo-sensei reveals to the remaining gems on earth that he is a different being with an origin different from their own, and further tells them that he had been trying to make a pure land for them but it only resulted into conflicts. He finalizes it by stating that they will have to continue without him, and that they should instead follow after one of their own, such as Phos. He also reveals his "official name", that being Kongou Daihijisho Jizo Bosatsu.
- Kongo-sensei rebuilds Phos 250 years after the gems tear them apart and momentarily accepts Phos' request to pray
The Gems love and trust him, and most of them obey him. Sensei, in turn, loves and cares deeply for all of them. As well as being their leader and mentor, he also fills the role of parental figure for the Gems. He shows affection occasionally as if they were his own children - patting Gems on the head, letting them crawl on him, picking them up, and embracing them, among other things. He still shows a lot of discipline towards them, as the Gems are incredibly fearful of him if he becomes upset at them doing something wrong. Considering it was said that Phos is the only one to get away with saying such things to Sensei, it's assumed that he usually doesn't tolerate back-talk or sass.
The Gems have always had a inkling that Kongo-sensei has a connection to the Lunarians but according to Cinnabar they never discuss it openly and the Gems simply decided to trust him entirely. He also trusts them back as when Phos, the only one who can talk to Ventricosus' small form, told him that they could communicate with it and he believed them. He's happy when the Gems are happy, and upset when they're in trouble. The Gems that disobeyed him and ended up breaking themselves usually get yelled at, making them more broken.
Sensei has treated Phos like the rest of the Gems, in teaching them and showing them affection and leadership. He seems to give Phos a bit of lax in terms of Phos talking back for some reason, and it's not really explained. Even so, there are limits to how much he will tolerate Phos's disobedience and is not afraid to discipline them like with the others if pushed too far. An example being that when Phos was brought back to the school after secretly going to the ocean, despite being ordered not to, Sensei was furious with them for both disobeying his orders as well as putting themselves in danger, to the point he scolded them with his infamously powerful voice.
He has attempted to give them a job, continuously denying them patrol duty, their first job being writing encyclopedia entries. He is willing to give them patrol duty afterwards, showing more trust in Phos and allows Antarcticite and Phos to work together during the winter. He has never blamed Phos for any of the Gems around Phos being taken to the Moon, and has attempted to comfort them. Even when Phos began showing doubts towards him, he still treated them with respect and affection. Sensei and Phos's relationship is best described as a parent and child one, wanting nothing more than the Gem's safety rather than prying for details. Even after Phos has taken other Gems to the Moon with them, Sensei still does not talk negatively about Phos, telling the remaining Gems that it is understandable that Phos would have doubts in him with the secrets that he's maintained. Sensei never attacks Phos, and attempts to secretly repair them after the Gems have shattered them.
He let Phosphophyllite cling and hide underneath his robe. When Phos was lost in the sea, he was glad to get them back. He understands Phos' loss about Antarcticite and kindly guided them during the rest of winter. While Phos loves him too, Phos starts to doubt him after accidentally hear him calling the unusual Moon Person a name. When Phos found out that he has been using tiny pieces of himself to attack the Lunarians, he asked Phos to keep it a secret.
Sensei mentions he regrets Cinnabar's condition and how he feels like he's essentially locked them in the night away from the other Gems. He eventually tells Cinnabar that they're worth just being alive, when the latter was struggling with their body. Cinnabar themselves dodged Phos' question and said they're still observing him.
He welcomed Ventricosus, the ruler of the shell, as he thinks the shell is also another kind of gem.
Lunarians have never been seen attacking Sensei, rather they worship him and present him with gifts. This isn't fully explained until Aechmea explains that they are attempting to appease Sensei. The Lunarians are the spirits of humans who were not purified by prayer before the impact destroyed humans, so are essentially stuck in limbo as Western audiences may associate it with. This prevents them from moving on into becoming nothingness, trapping them in suffering and "angst". Sensei was the prayer machine meant to help spirits like them move on, but he hasn't done so because of either being broken or other restraints (such as morality) stopping him. Aechmea explains that at first, Lunarians showered him with gifts and praise, vowing to do anything for him to pray. The Lunarians attempt to persuade Gems to help them, but the Gems break themselves before any cooperation can be met. The Lunarians then took the Gems hostage and ground them to fine dust to cover their Moon, Aechmea explaining that it would allow Sensei to see what he has caused.
Chapter 80 reveals that the reason why he had stopped praying for the Lunarians was because doing so would destroy not only the Lunarians, but the Gems and Admirabilis as well.
Sensei has shown aggression at the mention of humans, showing that there is tension between him and the former species. This isn't explained however, but Lunarians being one of the closest members of the pieces of humans shows a hint of what it may be. The only specific human mentioned is the Doctor, the one who created him. He does give brief passing comments on humans occasionally, such as crying being a fault of them. It's assumed he sees humans as sinful and impure, full of negative traits, especially compared to the Gems he cares for now.
The kanji used in Kongo (金剛) is derived from the Buddhist term Vajra, which means both "diamond" and "thunderbolt". A vajra is a symbol representing a force that is both indestructible and able to cut any substance (hence diamond), as well as unstoppable (hence thunderbolt). A vajra is often represented by a mace used by the Hindu god Indra.
"Adamant" seems to be a fan translation of Kongo. Adamant is a term used to refer to any especially hard, unyielding substance, whether composed of gemstone or some type of metal. Both adamant and diamond derive from the Greek word αδαμαστος (adamastos), meaning "untameable". Adamantite and adamantium (a metallic name derived from the Neo-Latin ending -ium) are also common variants. In the past, the term "adamant" has been used to refer to very hard materials such as diamonds. Today, adamant is often used in literature and other works of fiction to refer to a fictional substance that is unbreakable.
Kongo-sensei may be hinted to be a specific type of diamond called lonsdaleite based on the hexagonal pattern of his robes. This type of diamond is made of carbon atoms arranged in a hexagonal lattice. Theoretically, pure lonsdaleite is ~1.5 times harder than the usual cubic diamond.
Although Kongo-sensei is not a true Gem and is in fact a machine created by humans, he still has a diamond like outer shell.
- 金剛/Kongō means 1. vajra (indestructible substance); diamond; adamantine 2. thunderbolt; Indra's weapon; Buddhist symbol of the indestructible truth.
- Kongo appears to be based on and shares a number of parallels with Ksitigarbha, also known as Jizo in Japan. Ksitigarbha is a Bodhisattva who is primarily revered in East Asian Buddhism, who is usually depicted as a Buddhist monk, and is regarded as both a guardian of children and patron deity of deceased children in Japan.
- The reason why he wears Buddhist monk attire may because one of his Japanese name's meaning, other than the fact he adapted one of 'human' religion/tradition.
- Kongo bears a resemblance to a character in one of Haruko Ichikawa's one-shots prior to Houseki no Kuni, Star Lover. The story focuses on Satsuki and Tsutsuji, two sentient humanoid plants, both created by the former's "uncle", a plant biologist. Kongo-sensei happens to be resemble the biologist in particular.
- Kongo-sensei so far is the only adult-like Gems shown.
- Kongo-sensei's design in volumes 1-3 differed slightly in terms of facial features and stature. In earlier chapters, his facial features were slightly more gentler, sharper and with his chin being more rounder. His eyes were also drawn differently in comparison to later chapters. By the fourth volume and onward, his facial features became more angular and slightly squarish. His shoulders have also become broader by chapter 21.
- Kongo-sensei/Kongō-sensei and Cinnabar/Shinsa are the only gems who use Japanese names instead English in original Japanese version.