Get To Know TST Profile, Two-time Name Change, Recent Activities, And More


Meet TST, The Group That Has Changed Its Name Two Times Already

Usually, it is uncommon for a K-Pop group to change its name. Unless there’s a reason behind it, or whether or not they move to a different agency and can no longer use their name, it usually stays until the group is disbanded. To be fair, it is kinda hard to build a reputation with the new name. Well, meet TST, a group under JSL Company which has already changed its name two times. Since their debut on January 1st, 2017, the group has changed the name from 7STONE to Top Secret to now TST. The group currently consists of five members (Ain, K, Wooyoung, Junghoon, and Yonghyeon), after member Yohan’s shockingly sudden death in June 2020.

Are you curious about the group’s story? Scroll down the article below to find out more about them!


TST Group Profile


Previously known as 7STONE and Top Secret, now TST (일급비밀), first made their debut on January 1st, 2017, under JSL Company (now known as KJ Music), with the mini-album Time’s Up with the title track “She.” They first debuted with the name Top Secret in 2017 before changing it to TST in 2018.

The group originally debuted with seven members Ain, K, Wooyoung, Junghoon, Yonghyeon, Yohan, and Kyeongha. But, Kyeongha left the group on June 11th, 2018, due to his sexual assault case, while member Yohan, unfortunately, passed away at the age of 28 on June 16th, 2020.

Now, the group consists of five active members Ain, K, Wooyoung, Junghoon, and Yonghyeon.

Group Information

  • Group name: TST
  • Origin: Seoul, South Korea
  • Genres: K-Pop
  • Years active: 2017–present
  • Debut Date: January 1st, 2017
  • Label(s): KJ Music
  • Current members: Ain, K, Wooyoung, Junghoon, and Yonghyeon
  • Former members: Kyeongha, Yohan
  • Fandom Name: HANA (하나)
  • Official Accounts:
    Twitter: @FS7_official
    Facebook: officialFS7
    Instagram: @fs7official
    Fan Café: Daum Cafe
    YouTube: 일급비밀 TST Official


TST Members Profiles and Facts


Ain Profile

Stage Name: Ain (아인)
Birth Name: Kim A-in (김아인)
Position: Leader, Main Dancer, Vocalist
Date of Birth: February 15th, 1994
Zodiac Sign: Aquarius
Height: 182 cm (6’0″)
Weight: 64 kg (141 lbs)
Blood Type: O
Twitter: @AIN8008
Instagram: @ainismxx
YouTube (shared with Yohan): YO-I요아이


Ain Facts

  • Asan, Chungcheong, South Korea, is his place of birth
  • He didn’t make it when auditioning for JYP Entertainment
  • Choreography is his specialty
  • He used to be a dance teacher before his debut
  • Tonkatsu is his favorite food
  • Red and purple are his favorite colors
  • Wonder Girls, EXO, and Big Bang are his favorite idols
  • He used to be a member of NOM
  • On April 6th, 2020, he enlisted in the military


K Profile

Stage Name: K (케이)
Birth Name: Kim Hyeong-in (김형인)
Position: Lead Vocalist
Date of Birth: May 6th, 1991
Zodiac Sign: Taurus
Height: 178 cm (5’10″)
Weight: 63 kg (139 lbs)
Blood Type: AB
Twitter: @ghn5613
Instagram: @kimkei0101


K Facts

  • Gwangju, South Korea, is his place of birth
  • He can speak English
  • White is his favorite color
  • When it comes to food, he is not picky since there’s no food he doesn’t like
  • He often has insomnia
  • Super Junior is his favorite idol
  • He used to be a member of NOM
  • He has his own brand called Mellow Wolf
  • A girl with beautiful eyes is his ideal type


Wooyoung Profile

Stage Name: Wooyoung (우영)
Birth Name: Choi Woo-yeong (최우영)
Position: Lead Dancer, Vocalist, Rapper
Date of Birth: May 14th, 1996
Zodiac Sign: Taurus
Height: 178 cm (5’10″)
Weight: 60 kg (132 lbs)
Blood Type: A
Instagram: @wy0514


Wooyoung Facts

  • Sexy, cute and charming is how he describes himself
  • He can speak English fluently
  • Danny Choi is his English name
  • He’s fluent in English because he studied in California for seven years
  • Korean chicken is his favorite food
  • A bracelet is his good luck charm
  • Due to body discomfort, he is not participating in TST’s 2020 comeback


Junghoon Profile

Stage Name: Junghoon (정훈)
Birth Name: Lee Jung-hoon (이정훈)
Position: Rapper
Date of Birth: October 18th, 1996
Zodiac Sign: Libra
Height: 175 cm (5’9″)
Weight: 58 kg (128 lbs)
Blood Type: AB
Instagram: @hoon2_jung


Junghoon Facts

  • He is the rapper in the group
  • He participated in KBS2’s The Unit and passed the auditions but was eliminated after the 1st round, where he performed Block B’s “HER”


Yonghyeon Profile

Stage Name: Yonghyeon (용현)
Birth Name: Kwon Yong Hyeon (권용현)
Position: Main Vocalist, Maknae
Date of Birth: December 18th, 1996
Zodiac Sign: Sagittarius
Height: 175 cm (5’9″)
Weight: 58 kg (128 lbs)
Blood Type: AB
Instagram: @yyyyyyonggg


Yonghyeon Facts

  • He is the main vocalist and maknae of the group
  • He is known to greet fans through his personal Instagram account
  • On his Instagram, he uploads his daily photos, both when doing individual activities and when with TST


The Late Yohan Profile

Stage Name: Yohan (요한)
Birth Name: Kim Jung-hwan (김정환)
Position: Vocalist
Date of Birth/Death: April 16th, 1992/June 16th, 2020
Height: Aries
Height: 180 cm (5’11″)
Weight: 64 kg (141 lbs)
Blood Type: O
Twitter: @K_jeonghwan
Instagram: @yohanee0416
YouTube (shared with Ain): YO-I요아이


The Late Yohan Facts

  • Ulsan, South Korea, was his place of birth
  • He could play the drums and the piano
  • He was a fan of various boy groups like VIXX, B.A.P, BTOB, and INFINITE
  • Watching movies was his hobby
  • He used to be a member of NOM
  • On June 16th, 2020, it was announced that he passed away at the age of 28 and the cause of his death has not been revealed

Debut as Top Secret

The group first debuted with seven members (Ain, K, Wooyoung, Junghoon, Yonghyeon, Yohan, and Kyeongha) under the name Top Secret before changing it to TST on April 3rd, 2018. Produced by label KJ Music, they released their first mini-album titled Time’s Up with the song “She” as the title track on January 4th, 2017.

The song is a catchy beat pop music with easy lyrics that repeats “it’s love” as the hook. They use the school boy’s concept as the main theme of the MV that reminds us of a fresh youth and school prince charming. Their MV also has been talked to resemble boy group SEVENTEEN’s early concept, which they admitted as their role model.

Now, the MV has been watched for more than 101,000 times and is welcomed warmly by fans.

“2017 has just begun and I have already found my favorite debut of the year,” one user wrote in the comment section.

“Honestly… When they said Seventeen as their role model make Carat interested to know them,” another user wrote.

“They are looking like them boys in Otome dating games 😂😂💜 <I secretly love it>” another user commented.

They performed their debut song on their stage showcase in January 2017.

Check out their fresh performance below!



Extended Plays

  • Time’s Up (2017)
  • Wake Up (2017)


  • “She” (2017)
  • “Mind Control” (2017)
  • “Love Story” (2018)
  • “Paradise” (2018)
  • “Wake Up” (2019)
  • “Countdown” (2020)



In 2018, TST’s former member Kyeongha’s name suddenly surfaced after the court found him guilty of a sexual harassment case. The judge ruled that Kyeongha be sentenced to 18 months in prison with a trial period of three years and the obligation to attend rehabilitation for sex offenders for 40 hours.

The harassment case involving Kyeongha occurred in 2014 before he became an idol singer member of TST. He was reported by his female friend, A, on charges of rape.

In a police inspection, Kyeongha claimed he felt a sexual urge for A while walking together in December 2014 when he was 16 years old. Because A refused Kyeongha’s wishes, A tried to run away, but Kyeongha chased her to the first floor of his apartment building.

After that incident, Kyeongha apologized to A and admitted his mistake. But Kyeongha’s attitude changed since he debuted as an idol singer. That prompted A to open the case by writing his story on Facebook. But the agency of TST denied all of A’s accusations against Kyeongha. Refusing to remain silent, A filed a lawsuit against Kyeongha in April 2017.

Despite being found guilty, TST’s agency continued to evade allegations of sexual harassment directed by A against Kyeongha and intended to appeal and plead innocent.

“It’s true that [Kyeongha] received his sentencing at the first trial, but the forceful harassment accusations are absolutely untrue. We will fight back until the end,” said the agency’s representative.

“We continue to deny the allegations and plan to continue promotional activities, as usual, this is why we appealed,” they went on.

At that time, Kyeongha and TST just made a comeback with the release of the single “Love Story” on May 23rd, 2018.

This decision then caused TST to be banned from performing on Mnet’s music show M Countdown. Mnet revealed that they canceled TST’s performance due to Kyeongha’s sexual assault case.

“TST was in the final line-up for M Countdown, but after confirming the truth with their label, we decided to cancel their broadcast appearance,” a representative from Mnet said.

Shortly after that event, on June 11th, 2018, KJ Music announced that Kyeongha has decided to leave the group. The agency said that Kyeongha doesn’t want to jeopardize the group’s future so he decided to take a leave from the group. This decision was made after a long discussion between the label and the members.

Below is the agency’s full statement:

“Hello this is JSL Company.

“First, we would like to thank all of the fans who loved and supported TST. We would like to announce an update regarding TST’s future promotions.

“Currently, the TST members are considerably worn out mentally ever since their promotions have been halted. They are going through a difficult time.

“Lee Kyeongha has expressed his wishes to leave the group in order to prevent any more inconvenience to the other members. He has decided to leave the group.

“After learning about his wishes, JSL Company, Kyeongha, and all of the TST members discussed about it in depth. To respect his wish to prove his innocence against the false news going around, we decided to accept his proposal to leave the team.

“We would like to sincerely apologize to the fans and everyone that was inconvenienced by the controversy, and we will update everyone regarding the group’s future promotions whenever they are confirmed.

“JSL Company and TST will work hard to pay back everyone’s love and support by promoting with good music and activities. TST promises to do everything that they can for the fans.

“We ask for your unwavering support and love towards TST.

Thank you.”

Since then, the group continued doing promotions with the remaining six members until 2020.


Latest News

A piece of sad news hit the K-Pop music world earlier this year. One of the members of TST, Yohan, unfortunately, passed away on June 16th, 2020.

Yohan died at the age of 28. Yohan’s death left deep sorrow not only in his family but also among his fans. The cause of Yohan’s death is still unknown to date. The family requested that the cause of death of the TST member born in 1992 is not revealed to the public.

KJ Music Entertainment released an official statement shortly after the news:

“Hello. This is TST’s label, KJ Music Entertainment.

“We are sad to relay the most unfortunate, sorrowful news. Back on June 16th, TST member Yohan left this world. 

“The late Yohan’s family is currently in deep mourning. The family has pleaded that media articles about Yohan’s passing, such as those making speculations about the cause of his death, be refrained out of respect. 

“We express our deepest condolences in light of Yohan’s final parting.”

In April 2020, Yohan had just celebrated his birthday. Together with TST, he also celebrated the fourth TST album which was released in January 2020. He also shared those happy moments on his personal Instagram (@yohanee0416), saying that he was happy with the birthday greetings from fans and friends and it was the best birthday he has had.

Among other members, Yohan is one of the youngest TST members along with K who is currently undergoing military service.

Yohan’s latest post on social media Instagram was in the spotlight right after the news of his death. He was reported to have last given an update to fans on May 31st, 2020.

At that time, Yohan uploaded a number of photos of him while traveling. He took pictures on the beach to stand on the bridge against the background of tall buildings.

In the photo caption, Yohan expressed his desire to travel again. “I want to go out again,” he wrote.

After the news of his untimely death, fans flooded the post with expressions of grief. Many said they did not believe the news of Yohan’s death.

“I still can’t believe!” wrote one fan.

“My heart hurts. I will miss you and love you. I hope you rest in peace. You are an angel and I hope we can meet again,” added another fan.

We offer our deep condolences to the family and friends of Yohan and we wish him to rest in peace.

View this post on Instagram

여행가고 싶다✈

A post shared by 김요한 (@yohanee0416) on



So, those are all the things that you need to know about boy group TST. Don’t forget to kindly leave a comment in the box below to show your support for the group!