Double S 301 Member Profiles (2026 Updated)

Double S 301 — also written as SS301 or 더블에스301 — is one of the most beloved K-pop sub-units to come out of the legendary SS501 era. If you’re a longtime fan of 2nd generation K-pop, you already know these three guys hold a very special place in the history of Korean pop music. And if you’re just discovering them in 2026? Well, you’re in for a treat.

This group brings together three powerhouse performers: Heo Young Saeng, Kim Kyu Jong, and Kim Hyung Jun — three members who have proven time and time again that their bond goes well beyond just making music together. Whether you’re searching for Double S 301 member profiles, their discography, or their concert and tour history, you’ve landed in the right place.

In this guide, we’re breaking down everything you need to know about SS301 in 2026: who the members are, what they’ve accomplished, their music, their tours, and some fun facts you probably didn’t know. Let’s get into it!

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Double S 301 started as a sub-unit of SS501, one of South Korea’s most iconic 2nd generation boy bands. The group came together when three of the five SS501 members — Heo Young Saeng, Kim Kyu Jong, and Kim Hyung Jun — continued performing together while the other two members (Kim Hyun-joong and Park Jung-min) were busy with solo projects and acting roles.

Their unofficial start goes back to 2008, when they performed and released music under the name SS501 Special Project Group. Then in 2016, they officially rebranded as Double S 301 under CI Entertainment and released their proper debut album.

Here’s a quick look at the essential facts:

• Full Name: Double S 301 (더블에스301)
• Also Known As: SS301, SS501 Special Project Group
• Origin: Seoul, South Korea
• Genres: K-pop, J-pop
• Sub-unit of: SS501
• Label: DSP Media (2008), CI Entertainment (2016–present)
• Official Debut (as Double S 301): February 16, 2016
• Unofficial Debut (as SS501 Special Project Group): November 21, 2008
• Fandom Name: Triple S (SSS)
• Fan Color: Pearl Light Green
• Members: Heo Young Saeng (Leader), Kim Kyu Jong, Kim Hyung Jun
• Active Years: 2008 (unofficial), 2016–2017 (official)
• Status: On hiatus (as of 2026); members active in SS501/Five O One reunion activities

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The Band Member Profiles

Member Overview Table

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Heo Young Saeng — The Leader (허영생)

Heo Young Saeng is the heart and soul of Double S 301. As the group’s leader and main vocalist, he’s the one who holds the trio together both on stage and off. Known for his smooth, powerful voice and his natural charisma, Young Saeng is the kind of performer who makes every note feel personal.

He trained at SM Entertainment for two and a half years before joining DSP — which means he was almost a member of some very different groups!

Young Saeng was the first member of SS501 to compose his own music, showing just how musically gifted he is beyond just singing.

His solo mini-album Let It Go (2011) shot straight to #1 on the Gaon Music Chart on its release week.

He appeared in the stage musical “Haru” after completing his military service — showing off his acting chops alongside his singing talent.

Young Saeng held two sold-out fan events — one in Korea and one in Japan — right after being discharged from the military in 2015.

He can play the piano, and he often incorporates music composition into his creative process.

His fanclub name Y.E.S. is a clever acronym built from his name — Young Saeng, of course.

Because he trained with future members of Super Junior and TVXQ at SM, he has a surprisingly wide circle of K-pop industry friends.

He became the leader of SS501’s project group in 2008 when Kim Hyun-joong and Park Jung-min were busy with acting and other projects.

Young Saeng was part of the Five O One reunion project in 2025, when three of the original SS501 members came back together for their 20th anniversary world tour.

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Kim Kyu Jong — The Center (김규종)

If you’ve ever watched Double S 301 perform live, you know exactly why Kim Kyu Jong holds the nickname “Center.” His screen presence is magnetic, and his ability to balance rap and vocals makes him an incredibly versatile artist. He’s often described by fans as warm, humble, and sweet — and those who’ve met him say that’s not just a stage persona.

His fans call themselves “thanKYUs” — easily one of the most clever fandom names in K-pop, don’t you think?

Kyu Jong and Park Jung-min used to co-host SBS’s “Youngstreet” radio together — a fan favorite show at the time.

He temporarily took over as sole DJ for Youngstreet when Young Saeng had to take time off for throat surgery in 2006.

His musical theatre debut was in Goong: The Musical in 2011, where he played the male lead — Crown Prince Lee Shin — first in Tokyo and then in Seoul.

When he left DSP Media in 2010, he and Young Saeng moved to B2M Entertainment together, showing how tight their bond truly is.

He was born in Jeonju, a city famous for its traditional Korean food culture — bibimap capital of Korea!

Kyu Jong’s motto is “No regrets — I would like to challenge all!” and honestly, his career choices reflect exactly that.

He is known for doing magic tricks as one of his personal talents, which has surprised fans at fan meetings over the years.

His ideal partner is someone described as pure and honest — someone who shows their true self without pretense.

Kyu Jong participated in the 2025 SS501 reunion discussions along with Young Saeng and Kim Hyun-joong, cementing his place in the next chapter of their story as Five O One.

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Kim Hyung Jun — The Maknae (김형준)

Kim Hyung Jun is the youngest member — the maknae — of Double S 301, and like most maknaes in K-pop, he’s managed to break every expectation people had of him being “the baby” of the group. He’s a confident solo artist, a skilled DJ and MC, and a genuine entertainer who has built a strong career both in Korea and Japan.

His younger brother Kim Ki-bum (stage name: Allen Kim) is a former member of the boy group U-KISS — making the Kim family seriously one of K-pop’s most talented households.

Hyung Jun was the first K-pop idol to ever perform in Bolivia — a truly pioneer moment for the spread of Korean music in South America.

He and Park Jung-min went to the same high school — Dongguk University Teacher’s College High School — making their bond one of the longest in the SS501 family.

Hyung Jun was so well-loved in Japan that he is credited with helping popularize the Korean word “maknae” internationally, getting non-Korean fans to use it naturally.

Along with his younger brother, he co-founded HnBcompany — standing for “Happy n Bright” — a character design brand whose first product was PiroPiro, a sleepy-eyed bear.

He can play both piano and guitar, and his musical range extends from upbeat dance tracks to soft R&B ballads.

His theatrical debut in the musical “Caffeine” (2011) had him playing a barista — a charming, romantic comedy role that fans absolutely adored.

As a DJ and MC, Hyung Jun has hosted and performed at numerous events, showing a versatility that goes beyond just singing and dancing.

He signed with Avex Trax for his Japanese activities — one of Japan’s biggest music labels — giving him a strong and independent presence in the Japanese market.

After his military discharge in December 2018, Hyung Jun expressed interest in rejoining group activities, and fans have been hopeful for a proper Double S 301 return ever since.

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Achievements

Double S 301 has packed a lot into their relatively short active period, and their legacy stretches back even further through their work as part of SS501. Here’s a look at what they’ve accomplished:

• Song of the Month at the 32nd Cyworld Digital Music Awards (March 2009) for “U R Man,” released under the SS501 Special Project Group name — their very first major recognition as a trio.
• Their 2016 comeback album “Eternal 5” was a massive success, with concert tickets in Seoul selling out within minutes of going on sale.
• Double S 301 expanded their footprint into Japan with the release of their Japanese mini-album “Eternal S” (2016), followed by concert dates in Tokyo and Osaka.
• Their concert series “U R Man Is Back” (2016) in Seoul drew huge crowds and an encore event was added due to overwhelming demand.
• All three members have built successful solo careers in music, acting, and musical theatre — with multiple charting albums and theatre credits each.
• The group’s parent band SS501 made history as one of the first South Korean groups to win Best New Artist at the Japan Gold Disc Awards — a record that all three Double S 301 members share as a legacy achievement.
• As part of the SS501 / Five O One reunion in 2025, Heo Young Saeng and Kim Kyu Jong (alongside Kim Hyun-joong) returned to the world stage for their 20th anniversary tour, reminding a new generation of fans why this group was special.

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Discography and Music Videos

Double S 301 has released music both as their current group name and under their earlier project group identity. Here’s the full picture:

Albums & EPs

Key Music Videos

• “U R Man” (2008) — The track that launched the trio’s identity and earned them Song of the Month.
• “Pain” (2016) — The emotional comeback single that marked their official debut as Double S 301 and instantly trended across Korea.

• “Remove” (2016) — The title track of their Eternal 01 mini-album, featuring a dramatic, aesthetically striking music video that showed a new side of the group.

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Live Performances and World Tours

Double S 301 brought serious energy to every stage they stepped on. Their tours featured tight choreography, live vocal performances, and the kind of fan interaction that only comes from years of experience on stage.

Tour History Table

About the 2025–2026 Five O One Tour

While Double S 301 as a named group has been on hiatus, fans got their closest thing to a reunion when — in May 2025 — it was announced that Kim Hyun-joong, Heo Young Saeng, and Kim Kyu Jong would reunite as Five O One for SS501’s 20th anniversary world tour, kicking off in Seoul in July 2025. The tour celebrated the legacy of all five original members and gave Double S 301’s core lineup another chance to connect with fans worldwide. The group even released a new Korean studio album, Set it Off, in March 2026.

As for Kim Hyung Jun — fans are still holding out hope for a full Double S 301 reunion. His chemistry with his bandmates has always been undeniable, and there’s no shortage of Triple S fans ready to fill a stadium the moment that announcement drops.

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Final Thoughts

Double S 301 may not have had the longest run as a named group, but what they created — in music, in live shows, and in the hearts of fans — has genuinely stood the test of time. Heo Young Saeng, Kim Kyu Jong, and Kim Hyung Jun each brought something unique to the table, and together, they made something bigger than the sum of their parts.

Whether you’ve been a Triple S since the SS501 days or you’re just now discovering these incredible artists in 2026, there’s so much to appreciate about this group. Keep an eye on their solo projects, follow the Five O One reunion developments, and never stop streaming “Pain” — because honestly, it still hits just as hard as it did in 2016.