Che Yongtai

Che Yongtai is a student from Xiahou High School who lives a double life as a guardian and protects normal humans from monsters. He is the reincarnation of a demon lord that massacred and almost conquered the human world more than a century ago. Due to his actions and relevance in the series, Che Yongtai can be considered the deuteragonist.

Background
According to demon legends, a century ago, two arrogant demon lords massacred the human world and the Underworld, killing thousands of people and demons indiscriminately. The two eventually met their demise when both humans and demons sent out all of their strong warriors to fight them and used multiple tactics against them, which they barely won with. After being killed, their souls resided in the Blood Pool in the Underworld and recovered for the next hundred years. Eventually, they were able to reincarnate into the two new demon lords Che Yongtai and Xi Sha, who then spent years in the Blood Pool maturing and occasionally fighting each other before being released by Yan Wen to obtain the Heaven Crystal.

According to Shi Ji, and later proven by Ye Yan after he time-travelled, in the year 1860, Che Yongtai's previous incarnation instigated a war in an attempt to conquer the human world during the Warring Period, which went down in human history as the XX War to conceal the supernatural contents from ordinary humans. He had three hundred lovers, Shi Ji being one of them, and his level of power was on par with Xi Sha's previous incarnation, who at that point conquered the Underworld. Due to joining the war when the humans have significantly weakened each other before his arrival, he was able to quickly conquer most of the human world. At one point, he was challenged by the strongest Nightwatcher of that time, who wielded five Demon Flags and was in his Night Conqueror mode, but easily defeated him and crippled his ability to fight. He was later ambushed by thirty powerful spiritual warriors, but managed to retaliate and kill half of them, though he did sustain major injuries. Afterwards, he retreated to his Demon Lord City and conjured up an impregnable magical protection barrier around the city, prohibiting others from entering the city or leaving without his permission. He then began to gather five hundred spiritual humans under the age of eighteen in his city, who he intended to use as blood sacrifices to heal himself and boost his strength. He killed Golden Lamp during the process after a failed assassination from the monk. Eventually, he was killed by the combined forces of Ye Liao and Xiahou Shan, Ye Yan's ancestors, Huang Yuanqing, Huang Xiaoyan's ancestor, and Ximen Lianyin, Ximen Guanren and Ximen Ruxin's ancestor.

In the new timeline resulting from Ye Yan's time travel, Che Yongtai's previous incarnation almost managed to survive the assassination attempt and kill the representatives of the Three Great Guardian Clans, but was instead beaten to death by Ye Yan.

Personality
Che Yongtai is often characterised as being unintelligent, arrogant, short-tempered, and aggressive. He refers to himself as 大爷 (Dà Yé) or 老子 (Lǎo Zi), pompous and assertive forms of "I", and others as "small fries" (杂鱼). In particular, he refers to Xi Sha as his "follower" (跟班). His short-tempered and aggressive attitude is also demonstrated multiple times throughout the series, as he always resorts to violence first when someone displeases him. Che Yongtai's simple-mindedness is also repeatedly emphasized, with him frequently being fooled, led to a trap, and tricked into revealing information due to his straightforwardness.

Che Yongtai is extremely amorous. Due to biologically going through puberty but never meeting a woman he considers attractive, he can be easily infatuated by beautiful women, even if they are his enemies. Talking to a pretty woman is enough to cause Che Yongtai to blush, while even the slightest perverted act with one could trigger a nosebleed from him, with more extreme acts causing heavier blushes and more intense nosebloods that could possibly incapacitate him.

He shows an intense rivalry towards Ye Yan, who he considers his love rival due to his relationship with Huang Xiaoyan. He, like Xi Sha, exhibits extremely jealousy when the two interact or say something that he misinterprets as them being intimate. This usually results in him attacking Ye Yan, and if accompanied with Xi Sha, evolves into a brawl.

After being involved with Ximen Ruxin's activities, it is revealed that Che Yongtai is a masochist, or awakened as one.

Appearance
Che Yongtai is a tall and muscular man with red hair, gray eyes, two horns on his head and a red tattoo on his neck. He is really handsome as stated by Bao Huajuan, who is extremely attracted towards him. He looks identical to his previous incarnation.

Before he met Ye Yan, Che Yongtai wore the Heavenly Demon Armor which helped him channel his energy to use certain techniques. After meeting Ye Yan in a metro station, Che Yongtai tried out a cosplay show with him by dressing up as a rabbit to attract girls and gave the armor to Ye Yan. After accidentally walking onto the train tracks for the underground subway, Che Yongtai was hit by a train and was taken to a hospital, where he saw the picture of person wearing a business suit and manifested said clothing, which became his standard attire. During the Double Devils Arc, he wore swimming trunks. During the School Play Arc, he dressed up as the queen from Snow White, the stepmother from Cinderella and ultimately as Sun Wukong from Journey to the West.

Abilities and Powers
Due to the reincarnation of the demon lord being inferior in quality, Che Yongtai does not retain even 10% of the previous demon lord's magic power or intelligence. However, he gained unbelievable strength, endurance, stamina and some special skills that are only rivalled by Xi Sha, another demon lord in exchange.

Equipment

 * Heavenly Demon Armor (天魔战甲): An armor worn by Che Yongtai's previous incarnation that helps him channel energy better and reduce his stamina exhaustion rate. The method of creating the armor is lost for a long time. By wearing the armor, Che Yongtai is able to successfully use offensive techniques that require large amounts of energy. Due to his lack of experience and power, without the armor the energy will disrupt inside Che Yongtai's body, causing him to faint whenever he tries to cast a powerful spell. As shown by Che Yongtai's previous incarnation, upon activating its secret function, the armor will be summoned onto him unless parts or all of it are stored in a different dimension. With the full set of armor, he can activate the armor's secret ability and temporarily triple his total strength for ten minutes when activated, which cloaks him in a blue light and causes his eyes to glow.
 * Inferno Mount (烈焰神驹): Che Yongtai's previous incarnation's mount. It was ridden by Che Yongtai's previous incarnation, but was killed by Ye Liao, Huang Yuanqing and Ximen Lianyin during their assassination attempt on him. This horse was not used publicly by Che Yongtai's previous incarnation until the assassination, which forced him to reveal its existence and disrupt all the strategies performed by the guardians. The Inferno Mount can move at high speeds, but its most significant power is its ability to defy gravity and fly in the air, though it isn't immune to techniques that forcibly attract it, such as the Species Extermination technique used by Ximen Lianyin in her Mortician form.
 * God Destroyer (诸神毁灭者): Che Yongtai's previous incarnation's treasured blade. The God Destroyer has the ability to create a cage of electricity that traps the people inside it regardless of its user's strength. The cage of electricty allows people from the outside to enter it, but prevents anyone but the user themselves from exiting. Additionally, the blade also possesses the ability to create an invisible barrier with a twenty meter radius around it that completes seals off all magic usage in it, including the user's and will trap the people within it for a day or until only one person remains alive within the barrier. Due to his lack of proficiency in magic, Che Yongtai could not obtain this blade, which requires magic to sustain. Shi Ji noted that this blade cannot change its size through transformation.

Normal Form (≤10%)

 * Supernatural Condition: Che Yongtai possesses a supernaturally powerful physical condition. He was able to throw a shot put ball with enough power to destroy a building, easily defeat Ye Yan in a fistfight, tear a limb off the Defender of the Double Devils. and casually defeat a mob of gangsters with just his fists. Durability and endurance-wise, he fought and remained unharmed after being hit multiple times by Deng Yuankui for one hour, who is strong enough to throw a person several hundred meters into the sky and knock back someone so hard that they could die from sheer impact, as well as not flinch at all from cutting off his own kidney with a knife. In stamina, he was able to beat down Cang Ri, a wolf monster whose stamina is ten times greater than a human's without showing any sign of fatigue seemingly forever.
 * Enhanced Senses: Che Yongtai possesses enhanced hearing and smelling. He was able to accurately hear Yue Wuer's speech despite him being some distance away. He was able to smell the stench of the Youth Pills created by Cang Ri, which even Ye Yan could not detect.
 * Age Detection: Che Yongtai can accurately estimate an individual's age by looking at them.
 * Organ Regrowth: Che Yongtai is capable of regrowing organs that have been removed from him, as seen when he repeatedly sold his kidneys to earn money and got his heart stolen by Yue Wushuang. If he puts effort into it, Che Yongtai can regrow a lost kidney within a day. Regrowing a heart seems faster, but causes him to suffer severe exhaustion after being revived.
 * Body Splitting Spikes (地刺分尸杀): With the help of his Heavenly Demon Armor, Che Yongtai is able to channel energy into the ground and create large spikes that can even shred a large demon into pieces.
 * Earth Spike Garrotte (地刺绞杀): With the help of his Heavenly Demon Armor, Che Yongtai is able to channel red energy into his hand and perform this technique, it is unknown what the technique looks like as he stopped after seeing three girls.
 * Mutilating Demon Hand (碎尸魔手): With the help of his Heavenly Demon Armor, Che Yongtai is able to channel green energy into his hand and perform this technique, it is unknown what the technique looks like as he was stopped by Ye Yan before he could use it.
 * Demon Lord's Fury (魔王乱舞): An unknown technique used by Che Yongtai offscreen.
 * Demon Lord's Thousand Hits (魔王千裂破): An unknown technique used by Che Yongtai to fight people offscreen.
 * Manifestation: Che Yongtai can manifest or summon simple objects such as clothing and a table with books. He can perform this spell with relative ease even without the Heavenly Demon Armor since it is simple and does not require much energy. However, he cannot manifest money since it defies the rules of the universe.

Previous incarnation (50-70%)

 * Age Detection: Che Yongtai's previous incarnation can accurately estimate an individual's age by looking at them.
 * Earth Magic (土系法术): Che Yongtai's previous incarnation has mastered Earth Magic and is able to create and manipulate a durable teal rock-like material through hand gestures and telekinesis. He was extremely proficient with this technique, as he was able to block Huang Yuanqing's Destruction Tag Concentrate Fire, fend off Ximen Lianyin in her Mortician form, and attack Huang Yuanqing with spikes simultaneously using the material without even moving.
 * Body Splitting Spikes (地刺分尸杀阵): Using the material created by his Earth Magic, Che Yongtai's previous incarnation could create large spikes that were capable of easily shredding a human into pieces.
 * Piercing Stone Rain (石锥爆雨): Using the material created by his Earth Magic, Che Yongtai's previous incarnation could rain down spike-like projectiles onto his enemies when he is in the air with the help of his Inferno Mount or the Hover technique.
 * Magic Dispelling Eye (破法之眼): Che Yongtai's previous incarnation possessed eyes that were able to ascertain the power behind magic attacks, even if they were purposely concealed. He was able to determine that Huang Yuanqing increased the power behind her Destruction Tag Concentrate Fire by looking at the spell tags and noticing that they have gotten brighter than before, even when she tried to conceal their power and make them appear weaker. These eyes could also detect hidden lifeforms, as shown when he looked at the huge boulder thrown at him by Huang Yuangqing and noted that there weren't any lifeforms or magical weapons hiding in it, although he was not able to detect Ximen Lianyin hiding in the shadows of the rock's cracks.
 * Teleportation (位移): Che Yongtai's previous incarnation possessed the ability to teleport a few dozen meters in any direction to evade attacks, but it seems to have a requirement in order to be used, which limits its usage to once during a battle. Additionally, he cannot use any defensive spells during the teleportation process.
 * Hover (滞空术): Che Yongtai's previous incarnation possessed the ability to hover in the air. This technique does not allow him to fly, and without enough magic, he will slowly descend to the ground.
 * Heavenly Demon God-Slaying Kill (天魔弑神杀): Che Yongtai's previous incarnation's strongest attack. After enveloping both of his hands with orange energy in the shape of spheres, the Demon Lord would then fly towards his enemies with both his fists stretched forward, which he uses to strike with. Ye Yan's Flag Demon Sui Fenger, who was a witness of the original assassination on the Demon Lord, noted that the technique was originally weaker due to the latter's weakened state and the lack of a complete armor, causing the energy to barely cover his fists. During the second time Ye Yan time travelled, he accidentally caused the Demon Lord to gain the full set of the Heavenly Demon Armor and triple his strength, which made the gathered energy roughly the size of the demon lord's whole body and much stronger than in the original timeline, almost causing the death of the entire assassination team.
 * Heavenly Demon Exploding Kill (天魔爆杀): A powerful punch done by Che Yongtai's previous incarnation by cloaking his fist with red energy. It was enough to severely damage Ye Yan in his Night Conqueror form while the Demon Lord had his power tripled.

Trivia
In Chapter 396, Che Yongtai broke the fourth wall by rejecting Shi Ji's offer to kiss, and said "the editors prohibit underaged kissing now. If we kiss, this manga will get reported". He and Shi Ji later found an excuse by saying they are both over a century old and are legally adults.