Yeon Yihwa/History

History
When she was very young, Yihwa was praised for her incredible flames after immolating a person with them. Yeon entered the Tower when she was 14 and passed the Second Floor with the highest scores. Afterward, it only took her 5 years to reach the 20th Floor without anyone's help, including her Family's. After failing many times before, she was later seen in the same test as Wangnan, having burned him and the rest of her team, causing them both to fail the test. At some point in her history, she asked someone for help in trying to control her flames but was rebutted as she was a member of the Yeon Family.

The Strongest Regular
She passed the Survival Round as a member of Prince's helpers, then came 3rd in the next test with a score of 22,384. This score, even though it was extremely high, apparently puts her to shame, because she missed. Apparently, if she had hit something with focus, the strength would have been immeasurable. When Viole announced that he would take no teammates, she yells at him and accused him of being so arrogant as to pretend to be a Slayer candidate. When he said with all seriousness that he was a part of the FUG, she was left speechless.

Bath
She decided to try to team up with Viole in order to pass the test as failing one more time would bring shame to her family. She plotted to use him and then after the test, she could eliminate him by seizing any openings. This way, she could avoid being thrown out of the Family for teaming up with a FUG member. She mistook Viole for a girl and called him "Miss Grace", probably because she had only roomed with other females. However, she received a rude shock when "Miss Grace" walked into the spa section meant for males.

The Untrustworthy Room
She tried to stop Viole from attacking the other Regulars to get through, but her flames were easily stopped. Later, two Regulars managed to control her. In that marionette state, she released her flames which caused havoc around her and forced Prince, who unknowingly helped those two, to run away from her to his room. Yihwa was forced to attack Horyang who showed up to Prince's room in order to rescue him, but she stopped once she was freed by Viole.

FUG
Yihwa passed the 20th Floor test after surviving Mule Love's challenge. She believed that people from FUG were bad people who are not to be trusted; however, she was also one of Viole's teammates while knowing that he was a member of FUG. Convinced that Viole was terrorizing the Regulars in the shopping district, she followed him to a karaoke bar. There, she met Hwa Ryun and a very surprised Viole. She then started yelling at Viole when Ha Jinsung suddenly appeared. She continued shouting at him despite her knowing he was a High Ranker and Viole had to knock her out. That night, she went up to see Viole and burned Wangnan when he teased her about Hwa Ryun being prettier than her.

Flower of Zygaena
During the test, it was found out that the other team ran away after hearing that Viole was on their team. The test administrator decided to create a new test for the team. The team had to find Zygaena's flower, a gem that grew inside of Zygaena. Yihwa entered Zygaena with the rest of her teammates to search for the flower. She was left behind when Viole ran on ahead after he sensed the presence of someone with uncommon power, who turned out to be no less than the infamous Irregular, Urek Mazino.

She joined the team in the effort to fight Urek, but they were unable to stop him.

Epilogue, Path
Later, after the encounter ended, she learned that the Yeon Family on the 21st Floor had been eliminating Zygaena's babies by picking the flower to prevent their growth. She became depressed by this but was manipulated by Hwa Ryun into taking action. She then desired to correct her Family's wrongs when she becomes a Ranker.

Connection
On the 28th Floor, she blew up the opposing team as they were pinned down with Goseng and Prince's Lighthouse. She then ran over to where Wangnan was, only to find the fight was already over.

Devil of the Right Arm
She and the rest of the team listened to Horyang tell the tale about his past. That night, after the team had decided to wear coats like Horyang's to greet Cassano, she stayed awake. When she heard that Wangnan, Prince and Akraptor were thinking about going after Viole and Horyang, she volunteered to hire a suspendiship in the name of the Yeon Clan.

Bet
When the four of them arrived at the Hand of Arlen, they were all awe-struck at the state it had been reduced to. As they hunted for Viole and Horyang, she got a reading of Viole's pocket. After Wangnan blew up the rubble with one of his Shinsoo Bombs, they found Koon underneath. They brought him home and she treated him, only to start burning the acupuncture needle. Koon woke up and was about to stab Wangnan, but everything was explained. Koon trained them for a month to pass the 29th Floor test, but she couldn't control her flames. On the night before the test, she repeatedly tried to attain accuracy with her flames, but the resultant explosions from her practice kept everyone up. Despite going to the test exhausted, they still passed.

Tower of God: Part 2 - The Workshop Battle
She arrived with Team Tangsooyook on the middle of the 30th Floor and stayed at the hotel that was booked for her team.

One Shot, One Opportunity
When the game started, she was in a lighthouse, watching the ocean view. She was sent by Koon to the Archimedes.

Archimedes
When she saw Rak for the first time, she mistook him for a dinosaur. After Koon left the room, Yihwa tried to calm Rak down, but accidentally burned him. She later offered him a piece of jelly, but Rak knocked it down for being blue like Koon, upsetting Yihwa and causing an explosion. When Rak was with Dan, she appeared with Quaetro and tried to take a picture of Rak.

Battle x Gamble
Alongside Goseng, she scolded Prince because he told Miseng she would never get stronger. When she participated in the group with Quaetro Blitz, she argued with Quaetro about using fire to burn other people excessively. Quaetro told Yihwa that she was afraid of her own powers. She eventually qualified for the next round.

The Truth
She skipped the party and went along with Rak to find Viole. Both snuck into the FUG hotel and during their search, they met Androssi, who also had the same goal in mind.

Tournament
Wangnan summoned her and she took part in the Development Tournament. She was with Development Team Tangsooyook when they heard about the result of the northern area and Viole's departure from the FUG team. She defended Viole saying, "He... He is a bad person, but Mr. Viole is not someone who would ditch his team!"

Thorn
She screamed and exited the room saying she did not like bugs, then was seen with Rak, Wangnan, and Akraptor trying to get Vespa out of the room. When they were called by Koon, she learned the whole truth about FUG's plan to convert Viole in a weapon.

When they got out to the battlefield, she teamed up with Rak while covering Wangnan. When Paul and Macha of Team Snake appeared, she and Rak teamed up to defeat them. After Beta appeared asking if they were friends of Viole, she denied it, saying she would never be friends with a member of FUG. When they encountered Beta again, Rak said Yihwa was Viole's wife.

Summoning
She, along with Rak and Laure, teamed up to take down Beta and protect Wangnan inside the summoning station. She managed to destroy Medina, the true vanguard, earning them enough points to summon Viole.

Closure
She aided Viole briefly in his fight with Beta and then watched as he happily reunited with Rak and Koon. She was glum as she was surprised Viole could make such a happy face. Later on, she, Akraptor and Quaetro searched for Horyang and only came across success when Xia Xia decided to reveal their locations.

Epilogue
She was sitting by Wangnan's bedside when he finally woke up, startling her. They talk briefly and then she tells him to come out and greet everyone. Chang later noticed her staring at Wangnan and commented that he wasn't the only one who had taken note of Wangnan's incredible regenerative ability.

Later on, her, Prince and Rak followed Baam around when he went on his date with Androssi (much to the latter's chagrin).

Prologue
Yihwa was reading up on the Hell Express and wondered whether to stay with her team or not, as more powerful foes were coming up. She later wondered what Wangnan might be hiding when Hwa Ryun appeared and asked her what was on her mind. Yihwa rebuffed her offer and Hwa Ryun told her not to dig too deep or she might find out about Zahard and the 10 Great Families' biggest mistake. Later on, she brought Viole to the meeting Hwa Ryun had organized.

Revolution Road
Yihwa appeared on the platform of the Hell Express with Koon and Wangnan and then teamed up with the latter when they took on Cassano. With coordinated attacks, the two managed to take the upper hand against the living Ignition Weapon until their fight was interrupted by the actions of Angel, who attacked Yihwa with her metal fish, and the Mad Dog, who attacked Wangnan. Before Rachel's group could escape into the Hell Express, Koon hurled her and Wangnan into the train after sealing them into the White Heavenly Mirror. After the train departed from the station and got a considerable distance away, she and Wangnan were freed from the blade's seal and got ready to execute their mission on board the train.

Hoaqin
She and Wangnan followed Rachel's group through the train thinking of a way to retrieve Hwa Ryun. When Rachel's group continued onwards, the two tried to follow but got stuck by the math-based puzzle. Struggling with how to solve it, Rachel's group unexpectedly came out and Wangnan tried to attack on Hwa Ryun's orders. However, Hoaqin effortlessly subdued his attack and the two were taken a hostage with Hwa Ryun. The two then witnessed Hoaqin's fearsome strength as the group passed the 36th Floor stage test.

Wooden Horse
With Angel and Mad Dog keeping an eye on them, the former laid down the cold truth to Yihwa when she tried to call FUG's actions out. When the train suddenly began rumbling, Angel and Mad Dog went to see what was happening, leaving Yihwa and Wangnan by themselves.

Using their lack of supervision to their advantage, the two got free and started navigating the train again. As they were walking down a pathway, they encountered a person they least expected to see. Realizing he was another part of Hoaqin, they followed him wondering what he would be like.

A Month
Vicente complained of being hungry and Yihwa gave him some banana-shaped chips to sate him. Vicente thanked them for the snack and he continued walking on, with Yihwa and Wangnan noticing how different Vicente was to Hoaqin. Deciding to pretend to take him to Hoaqin, the two began leading Vicente. Hearing noises, Vicente went to check it out and they soon encountered their previous captors fighting against Rak and other Regulars. Vicente chided them for making so much noise and stopped their fighting. Angel and Mad Dog tried to convince Vicente that Yihwa and Wangnan were his enemies, but Vicente defended them because they gave him snacks when he was hungry. Vicente then threatened Rachel's allies until Hoaqin arrived and contently reunited with his sibling. After some discussion between the two siblings, they clashed and Hoaqin told his allies to attack. Wangnan then sealed Vicente within the White Heavenly Mirror and their group fled the scene.

Later Wangnan freed Vicente from the blade when the latter agreed to help them stop Hoaqin and together they cleared the stages of the train they came up against. Yihwa was also present when Daniel struck a deal with the group. She later arrived at the 4th stage with the rest of the group in time for the game to begin.

The Dallar Show
Yihwa watched as the first round of the Dallar Show was quickly won by Koon, giving Team Viole the first win. With the second round game, "Transferring the sweetfish", beginning, Yihwa is partnered with Bero Bero and Hongjo. They soon encounter Angel and Buelsar Elliot in the pipes, and Yihwa strikes them both with fire to buy time and escape, though they soon end up in a fight with Angel as they bounce around in the pipes. Angel soon finds an opportunity to land a fatal blow to Yihwa, but she is countered by Hongjo. Yihwa soon falls to the ground as Hongjo can't carry her in flight, and she listens to Angel's speech about her hatred and the Great Families' hypocrisy.

She recalls a memory of trying to find a way to control her flame, only to hear that the Yeon Family is "flame itself." She then remembers a painful memory of burning someone with an incredibly hot flame, being congratulated and praised with having Princess potential. She resents this memory and strikes Angel with another flare, causing her to spread her wings wide open. As Angel attacks with powerful strikes and threatens to destroy the ground and send her to her death, Yihwa struggles to defend. Getting bored, Angel then impales Hongjo, killing and mocking him, sending Yihwa into a state of rage and raising her flame to a new level.

Yihwa then becomes hyper focused and unresponsive, using her flame to achieve flight as it envelops her body. Angel mocks and taunts her but soon grows scared of her ever-growing flame, which attacks her with tremendous power. Angel narrowly escapes the first attack but is roasted by a second. Before Yihwa can finish the fight, Bero Bero jumps into her flame and pleads with her to come back to her senses, reminding her of the standard she needs to set with her power and heritage. She succeeds in bringing her back but also sends them both into freefall before Baam flies in to rescue them.

Baam asks if Yihwa is alright, and naturally, she responds by accusing him of sexual harassment. She laments her loss of control, then listens with the team as a defeated Buelsar explains Hoaqin's true nature. While she doesn't believe Buelsar at first, she runs with Baam to save the others from being attacked. While they fly through the pipes to find Hoaqin, she asks if he's afraid of fighting a former slayer, which he confirms. They then arrive at Hoaqin's destination, right before he can kill Daniel.

She runs to an unconscious Wangnan, but Hoaqin blocks her path, taunting her. As Hoaqin explains the situation, she tries to attack, but her flame is put out by Hoaqin as he threatens to slit Baam's throat. Watching as Baam and Hoaqin duel, Sachi approaches her with a plan to create a diversion and an opening. She distracts Hoaqin with an attack in tandem with Sachi and Aka, but Baam still fails to land a successful blow. Though Baam later manages to strike decisively, he, Yihwa, and the others fail to do any real damage, and they are all transported to the final testing chamber.

During the final round, she can only watch as Baam succeeds in fighting Hoaqin and saving the hostages. She is relieved when her own teammates are saved, running to check on Prince once he's rescued. She then checks on Arkraptor, plagued by survivor's guilt. After the battle as the arena begins flooding, Yihwa uses Sachi's vines to escape before being rescued by Yuri and her shinsoo bubbles.

Yuri Jahad
She is surprised to learn her savior is actually Ha Yuri Zahard, but soon relaxes with the rest of Team Tangsooyook. During the test the next day, Yuri praises her abilities.

The Name Hunt Station
Yihwa attends Yuri's briefing describing Name Hunt Station, but when the time comes to depart, Wangnan tells her to go herself while the rest of their team stay on the train. Yihwa objects and pleads to Baam to stop this, but he responds by saying they have to take responsibility for their decisions. She follows Baam with the others off the train and encounters the no-named. Xia Xia then refers to her as one of Viole's faithful lords. The army of no-named then carry her and the other lords off to the no-named area.

On the way, she is distracted by an explosion and runs with Danhwa to discover the cause. She arrives at the site and finds Rak battling Inieta, hurling fire at him only to discover his swordsmanship blocks her flames. She tries to protect Danhwa from further attacks when Inieta discovers and steals his ignition weapon, but to no avail. Inieta then quickly defeats her as well with an ignited strike, capturing her and bringing her to Kaiser as bait to be sold at the auction.

When Karaka and Yuri begin to fight at the station, Yihwa runs with the others to the boarding platform to get to the train in time. She, Rak, and Danhwa are protected from a blast by Androssi and her Bong Bong, but Karaka appears in front of them to use them as hostages. Androssi and Yihwa then plan to create a diversion so that Androssi can save Viole, but this plan also destroys the platform they're on, sending her, Rak, and Danhwa into freefall.

The Floor of Death
Yihwa is seen recovering once again in a Wolhaiksong facility, having been rescued by Yuje. She is still unconscious.

The Hidden Floor
Now climbing the tower with Danhwa on Floor 41, the two wander through the desert and discuss why Danhwa is following Yura. She tries to find out why Danhwa is in love with her and hears his story about the mirror fragment, but soon forgets they were talking about anything as the Hidden Floor's protection mechanism kicks in.

Deng Deng
She was seen being knock down on the ground together along with Hong Danhwa by a snake man named Yool and a masked man named Kell, at the beginning of season or part 3, which happen somewhere at 44th Floor, several months later after the attack event of Zahard's Army at the Last Station.