After School RED

After School RED is a sub unit group that was created and form on the 4th July 2011 , it was announced that would be splitting up into two groups 'Red' and 'Blue' as part of a comeback project . With red unit will be they will displaying a sexy , fierce and tough concept while the blue unit would display a sweet,fresh and refreshing concept.

The members of the Red unit were Kahi, Jung-A, UEE and Nana, and the Blue unit consisted of Juyeon, Raina, Lizzy and E-Young. Kahi is the leader of A.S. Red, while Jooyeon is the leader of A.S. Blue, Although many criticized the group for having the majority of  popular members  in band and the less popular ones in group ( Lizzy, Raina , juyeon and E-young)  in the second group which many called a dull group. After school red release their first digital song   "In the night sky" which top charts , charting at 9th position.

Sistar19

Sistar debuted their first subunit in early 2011 featuring main vocalist Hyorin and rapper Bora. The 19 in Sistar represent young ladies that are transitioning  into Mature Ladies  and it also embodies 
the sense of innocence yet uncertainty they feel. They debut with song "Ma boy" and its was one of my favorite songs from them to this day although they made a comeback again with another hit song  "Not around any longer " in 2013  that would be the last song  to hear from them since Sistar have disband in 2017. But I always keep playing their song and continue to support each member.

Super junior -Happy

For a group who debuted with alot of members  who wouldn't be surprise that have include sub units as well.I believe super junior is the only kpop group that alot of Sub units I'm convinced . Funfact they were the first group that have the subunits. They have a total of five subunits which included K.R.Y ( Kyuhyun , Ryewook and Yesung ) the first  official subunit that formed in 2006 ,it
is comprised of the three best and most powerful vocals of Super Junior. The subunit contains Kyuhyun, Yesung, and Ryeowook. This subunit focuses on R&B style ballads, and often sings for various drama OSTs. For me, KRY is such a beautiful subunit and I am glad that it was formed.

Super Junior -T 

Super Junior-Trot is the second official subunit of Super Junior and was formed in 2007. They are the first idol group known for capitalizing trot music. This group specializes in Korean trot and the most well known song of theirs is Rokkugo which I really love, It conprises  of  six members such as Kangin , Sugmin , Heechul , Eunhyuk, Shindong  and Leetuek .And I have to say this was pretty good lineup and I really appreciate theyre comeback on the devil album.

Orange Caramel is a  sub group from After School that was formed back  in 2010  ,they are one of the very  first sub units of AS . The group consists of 3 members Lizzy, Nana and Raina . I love this groups and concept that they are doing, everything about them are so unique , one of my favorite song and i think everyone favorite song  was " Catellena " which was released back in 2014 to this day I still listen to it .Even though After School are on a very long Hiatus , I do hope some day they will reunite to perform this song again.

2YOON 

Even though its been 3 years since 4Minute disband , I would always continue to listen to all their songs and carry on their legacy they left behind. 2YOON is a Sub unit group that was formed early 2013 members Gayoon and Jiyoon also known as Jenyer formed this band and debut  their song "24/7" even though the group didn't enough promotion and attention that it wants . I have to say its a pretty good song.

Taetiseo

is the first sub-unit of South Korean girl group Girls' Generation, formed by SM Entertainment in 2012. It is composed of three Girls' Generation members: Taeyeon, Tiffany, and Seohyun. The group has released three EPs: Twinkle (2012), Holler (2014), and Dear Santa (2015).

Taetiseo  is made up of the first syllables of Each member Taeyeon , Tiffany and Seohyun. Their debut EP, Twinkle, was released on April 29, 2012. It was the first album by a Korean artist to rank number 1 on the Billboard World Albums chart.[ At the time, it was also the highest charting K-pop album on the Billboard 200, reaching number 126. 

Just recently Last year Sm formed another Sub unit for Girls Generation and that was called Oh! GG the sub unit is comprise of Taeyeon , Sunny , Hyoyeon , Yoona and Yuri . They debut with " Just a little touch"even though they haven't promote the song , I still wish to see them performing it live.

Infinite F

Infinite F (Korean: 인피니트F; stylized as INFINITE F) is the second sub-group of South Korean boy group Infinite formed by Woollim Entertainment in 2014. The sub-group consists of Infinite vocalists: Sungyeol, L and Sungjong. The sub-group made their simultaneous Japanese and Korean debuts with the single albums Koi no Sign and Azure.

Infinte H

Infinite H which H means Hiphop (Hangul: 인피니트H) is the first official sub-group of South Korean boy group, Infinite formed under Woollim Entertainment in 2013. The sub-group consists of Infinite members Dongwoo and Hoya. The sub-group debuted with their mini album titled Fly High and released their second EP, Fly Again, on January 26, 2015.

Dasoni is Sub duo that consists of Exid members Hani and Solji .It's been six years since we haven't heard any new music  from them but this song really truly catches me and it really moves me , to hani amazing vocals to Solji terrific high notes. This song truly deserves attention.