Yeo Goseng

Yeo GoSeng (여고생, Yeo Gosaeng; or "Yuh Gosaeng") is a Regular that we meet for the first time in Ch. 82.

Appearance and Personality
She ties her hair in a ponytail and also wears a pair of glasses.

She seems rather protective of Miseng and they both come from the same family and are of the same generation level. This is because they share the same surname "Yeo" (여) and they share the same generation name "Seng" (생): 미생 (MiSeng) and 고생 (GoSeng).

SIU has confirmed they're not sisters, insinuating they're most likely from the same family and know each other very well (probably cousins).

Abilities and Powers
Goseng is a lightbearer. She is sharp and knowledgeable and was the only person to notice that Viole was wearing a mark of the slayer from the FUG. She is one of the more mature member of the group and helps calm them at times.

Tower of God: Part 2 - The Return of the Prince
Yeo Goseng is the eighth person to enter the testing room. Ja Wangnan was about to attack her guiltlessly because she was not wearing a uniform. He was stopped when Miseng calls out to her, calling her unni. Kang Horyang's wing turns into hearts when he first looked at her. While they are waiting for the next person to come in, Wangnan starts to yell at everyone for being so compliant. When he shouted at Miseng, Goseng screams back at him and hugs Miseng. When the next competitor, Hon Akraptor, tries to vote Miseng off, Goseng yells at him to stop doing whatever he wanted. A fight breaks out between Akraptor, Horyang, and Jyu Viole Grace when Viole announces that he would drop everyone. After Viole blasts the two of them away with Shinsoo, Goseng identifies the mark he wore on his coat as those worn by slayers in FUG. This shocks everyone and causes them to fear Viole. She is seen hugging Miseng after Viole downs Horyang and Akraptor.

While they are waiting for the second part of the test to begin, Miseng gives everyone (but Akraptor) chips. Wangnan angrily asks, "What do you think this is, a picnic?!" to which Goseng smacks him and tells him to just eat it. She scolds Miseng when chips were given to Viole, telling her that she shouldn't do dangerous things. When another Regular made it out the elevator, bloody and weak, she stands up to help him but is stopped by Wangnan, who says that they would have to drop him later anyway.

Goseng scores worse than Miseng for the World's Greatest Shinsoo Contest. She is seen sitting against the wall along with the other Regulars who thought they had failed. When Wangnan starts to cry about his loss, she scolds him and tell him to be manlier and that his tears were making Miseng cry too. Faced with both their weeping, she gives up in trying to stop their tears. She is surprised by Wangnan's attempt to convince Viole to pick him. For reasons unknown, she never appealed to Viole to select her.

She encountered Akraptor and Horyang after they came out of the Baths. At that time, Miseng was crying. Then, Ja Wangnan and Nya Nia appeared with a pack of cards and entices the others to play.

She and Miseng are took part in a game initiated by Love. She takes the initiative by recruiting Wangnan. Later on she guards a room while Wangnan, Akraptor, and Horyang stole rooms. After the test, she is seen celebrating with the other passing Regulars.

On 21F, she is has stayed with the Regulars she passed with. She is living with them in the house Viole bought for them. When Viole brought home his fellow FUG members, she cut the fruit they brought as a gift (though she trembles in fear).

On the 21F test, the team is split into two groups. Goseng goes with Miseng, Wangnan, and Akraptor to search for the flower of zygaena that they were sent to retrieve. She uses her lighthouse to search for information and to slow down the pig like creature which has the flower on its back. After the test she sits with Miseng while waiting for Viole to wake up from his injuries. She also discusses with the others on the feasibility of them being able to help Viole.

Trivia

 * GoSeng's glasses are so round and big that they cover half of her face. We never see her eyes. It's unknown for now if she wears them because she has poor eyesight or because they aid her in battle, like Po Biduh Gustang's glasses.
 * Her name literally means "female high school student".
 * Like Miseng, there's a running joke about her being Enryu: Gosenryu.