TWEETY

On September 17, the group released their third digital single, "Hug Me". On December 2, Jiwoo was officially introduced as a new member. Later that month, on the 30th, the group released their fourth digital single, "Casual Boy".

In February 2016, Jiwoo stopped appearing in performances. TWEETY later started promoting as a trio, signaling her departure from the group. On July 28, they released their fifth digital single, "Badaya".

For the remaining of 2016, the group continued performing as a trio and was occasionally joined by undisclosed guest members. On November 26, the group held their first solo concert and revealed their upcoming track, "파이팅 아저씨", as well as new member Mirae. However, she ended up not joining the group officially.

In February 2017, the group began teasing their sixth digital single, "파이팅 아저씨", which was eventually released on May 26, 2017. Since June, Sia had been absent from group activities. On August 19, it was announced that she had entered a hiatus due to an ankle injury and would return once recovered.

In the same announcement, a new member, Aya, was introduced, with confirmation that the group would eventually become a four or five-member girl group once Sia returned. On September 9, another new member, Yuriel, was introduced. Around the same time, another member, Jaewon, joined the group but left shortly after.

In December, newly added members Yuriel and Aya also departed from the group, leaving TWEETY once again as a trio. On January 20, 2018, the group's SNS posted a new logo and revealed their new lineup, consisting of original members Haerin, Ain and two new members: Boreum and Hanul. This also indicated that Sia had left the group at some point in 2017, as no further updates about her were provided.

In the same post, they teased a new MV, set for release on the 23rd of the same month. However, the comeback ended up getting delayed for unknown reasons. On March 17, they made their long-awaited comeback with their seventh digital single "Bad Boy".

In June, Hanul stopped appearing with the group and a new member, ChaeA, was spotted performing with them, indicating that she had replaced Hanul. With this, they began teasing a comeback the following month. On August 30, they released their eighth digital single, "Badaya".

In September, ChaeA left the group and was replaced by Wonkyung the following month. On December 13, they released their ninth digital single "Run Run Run", which was used for the 2018 Gangwon Provincial Sports Festival. In early 2019, Ain presumably left the group as she was no longer seen in performances.

Subsequently, TWEETY spent the year actively participating in various concerts and events as a trio. On September 24, they released their tenth digital single "Happytree In Your Heart" to commemorate the launch of Shinil Happy Tree "The Roots" apartment located in Bupyeong-gu, Incheon. Shortly after this, both Boreum and Wonkyung departed from the group, making TWEETY a solo act with only Haerin left in the group.

On February 18, 2020, she made her solo debut with the digital single "Freak Out". Sometime after this, Haerin’s name was no longer listed on the company's website and the group's SNS became inactive, indicating that TWEETY had disbanded. Former member Wonkyung later confirmed on her YouTube channel that the group had silently disbanded sometime in 2020.