Why Aren't Sub-Units a Thing Anymore?

Another thing that has died out in recent years was the formulation of sub-units in K-Pop. An idea where within a main group, there would be another group containing some (not all) of the members attempting a different sound or genre to one that the group is normally known for. Since the beginning of the 4th generation, this is a concept that doesn’t really exist anymore except for pre-existing groups to suddenly debut a new duo or trio sub-unit (such as Monsta X’s HxS, the newly debuted Astro sub-unit Zoonizini, and the entire concept of NCT - these all came from 3rd gen groups.)

Whether it is because companies feel that sub-units would not work with these newer gen groups is definitely a question to be asked. Personally, I think its because there is already such an influx of groups in the market right now that having a sub-unit within all of that mess would be a waste of finances and resources for a company if that group hasn’t already made one before.

But I am not here to have a deep dive into the nitty gritty of the business decisions around sub-units (mayhaps another time?) I am actually here to have a nostalgic review about some of the sub-units that made an impact for me musically as well as the ones who were really successful overall.

And some of them that were just downright strange.

Super Junior-Happy, I am looking right at you.

Let’s begin!

INFINITE H
INFINITE H is my favourite sub-unit of all time and their first mini album ‘Fly High’ is in my top 5 greatest K-Pop albums. Featuring the rappers of the group, Dongwoo and (ex-member) Hoya, Infinite H was a hip hop unit featuring a more “urban” sound that did not feature that much within the early days of INFINITE’s discography with the legendary Sweetune. I remember when the unit was announced that I was extremely excited for it and I was not disappointed with their debut single, ‘Special Girl’ (featuring Bumkey). The unit had one more release before effectively disbanding in 2017 with Hoya’s departure from the main group. INFINITE had another sub-unit, INFINITE F featuring Sungyeol, L, and Sungjong but their music was a lot slower in tempo and not really what I was craving from an INFINITE sub-unit. They are technically still active, though their one and only release was in 2014. The group are active again though after all members served in the military and opened their own entertainment company so let's see what happens next?

AOA Black
AOA Black was the short lived band sub-unit of the group AOA. Made of the members Choa, Jimin, Mina, Yuna, and Youkyung it was meant to tie in more to FNC Entertainment’s specialty of having K-Pop bands (such as FT Island, CNBLUE, and N.Flying). The group debuted in 2013 with the song 'Moya' and it was a song that I had greatly enjoyed when it first came out. Particularly as I think the voices of Choa and Jimin suited a band/instrumental concept better than the music AOA were generally putting out as a group. They were listed as inactive by 2014 and considering the scandals that occurred in the group and the fact that all the girls have departed FNC, we are not getting a reprieve of AOA Black anytime soon. Which is a shame because, apart from the Wonder Girls short-lived revival, there weren’t any girl groups who were doing a live band concept at that time.

EXO - CBX

This sub-unit was, at the time, perceived as a bit random as it stemmed from a concert VCR from an EXO concert. Then they released a song for the soundtrack of the hit drama Moon Lovers: Scarlet Hearts Ryeo called 'For You' in 2016 which became a hit in Korea (particularly as the drama itself was really popular for international fans - I personally didn’t get the hype). After that, having Chen, Baekhyun, and Xiumin as the first sub-unit members of EXO just made sense. They were powerful enough to be the first members of EXO to leave SM Entertainment  as individuals and as the unit under Baekhyun’s own subsidiary, INB100. It’s worth noting that despite the move, they haven’t released anything as a group since 2019.

GD & TOP and GD x Taeyang

Iconic and legendary, BIGBANG have had two sub-units since their debut. GD &TOP appeared first in 2010 with their eponymous album that was one of the biggest sellers of that year and gave us amazing tracks such as “High High” , “Oh Yeah” and “Don’t Go Home”. After that, same aged friends GD x Taeyang released the single “Good Boy” in 2014 and I remember the madness that surrounded that song with how popular it was. At that point, BIGBANG was riding a multi-year high in terms of popular songs as a group and soloists so this was simply the icing on the cake. Good Boy is probably my favourite unit song though all that have been released are certified bangers.

Orange Caramel
The legends that are Orange Caramel cannot and should not be forgotten. I think I can name you about two After School songs but I can name you most Orange Caramel singles. Made up of the members Nana, Lizzie, and Raina, Orange Caramel were cute and quirky while their origin group were a lot more sultry and mature. Their bright costumes and catch tunes really worked for them with the intro routine of 'Shanghai Romance' trending on social media back in 2024 despite originally coming out back in 2011 but I guess when nostalgia hits, it hits HARD. The group had a run of about four years as they debuted in 2010 and their last release was in 2014 and since all of the members of After School have officially left Pledis, one can assume that (at least for now) Orange Caramel is a dormant group. We can cross our fingers for a return though if the resurgence of Gen 2 and 3 groups currently are anything to go by!

Irene & Seulgi
This is probably my most favourite girl group sub-unit of all time. When I first heard 'Monster' when it was released in 2020, I was instantly sold. Immediately. I was like, “Yes ma’am, I am here for this and all of it!” It helps that I am a huge fan of Red Velvet in general and that I adore Irene and Seulgi’s voices on all of their songs. 'Naughty' is a particular fave of mine also, especially with that wonderful music video and their precise tutting moves. They released a long awaited comeback mid 2025 with 'Tilt' which had that controversy with its cover artwork but nevertheless it was a great song!

TOHEART

I am including this sub-unit because of it’s interesting setup. We have had cross group units before (Troublemaker comes to mind with Hyunseung from B2ST and Hyuna from 4MINUTE) but TOHEART was the first (and only, at the time of writing) sub-unit that had members from different entertainment companies. The group featured Key from SHINee and Woohyun from INFINITE. More of a collaboration than anything, TOHEART was a projected that played to the fact that both Woohyun and Key were pretty much inseparable friends at the time (like on every variety show or on social media, one would constantly mention the other) so the unlikely combination of SM Entertainment and Woolim Entertainment gave birth to this one off project. It probably was only possible because, at the time, SM had partial ownership of Woolim but it had since sold it back to them. It was a strange time for sure. The lead single, 'Delicious', had some hype around it but it quickly fizzled out. ToHeart’s promotion period was only within 2014 but maybe there is a chance they could return?

And now for the big one. The group with the MOST official sub-units because, at the time of their debut, they had the biggest line up. I am talking of course about:

Super Junior.

As of 2025, here is the full list of Super Junior’s units:

Super Junior - K.R.Y, their first sub-unit featuring their main vocalists Kyuhyun, Ryeowook, and Yesung. They leant more towards ballads.
Super Junior - T, their trot sub-unit
Super Junior - H, also known as Super Junior Happy and they had more of a bubblegum pop sound.

Super Junior - M (not to be confused with another SM group, SuperM) - their Mandarin singing sub-unit that introduced two new members to the group: Henry and Zhou Mi (though after much protest from their fandom, they were never introduced to the full SuJu lineup after the original kerfuffle they had with Kyuhyun’s late introduction to the original lineup)
Super Junior - D&E, featuring members Donghae and Eunhyuk and they are actually my favourite sub-unit of the group.
Super Junior - L.S.S, the newest subunit debuting in 2023 featuring Leeteuk, Shindong, and Siwon.

There are a lot more that I have not mentioned, these were just the ones that made an impact on me and my own listening habits. However, I would be interested if there are sub-units out there that I haven’t talked about that you are all fans of. Let me know! Also, who in the current 4th and 5th gens groups should be put into a sub-unit? Maybe that could be a future write up!