A rush of veteran K-pop boy groups returning with new releases stirred up nostalgia among old K-pop fans and enriched the music scene.

That includes the so-called "second-generation" boy groups, those who debuted between 2003 and 2011, such as legends SHINee, Ukiss, Infinite, Teen Top and TVXQ.

SHINee started the comeback race with the release of its eighth studio album, "Hard," in June, breaking a hiatus of more than two years.

The group celebrated its 15th anniversary this year with the studio album and its sixth standalone concert in Seoul.

In a sign of its popularity, the quartet's three-day concert drew around 30,000 fans.

The concert was the first in almost seven years as the members had to report for mandatory military duty and also due to the COVID-19 pandemic.

SHINee debuted under SM Entertainment in 2008 and is recognized for its contemporary rhythm and electro-pop sound.

The band established a strong position in the K-pop scene with trendy music and outstanding performances.

Ukiss, a leading K-pop boy band in the 2010s, also followed suit.

After five and a half years, the group returned with its 12th EP “Play List” in June.

The EP, after a year in the making, is led by the title track “The Wonderful Escape,” a house pop single with a retro sound that brings back the explosive energy of Ukiss.

Ukiss debuted in 2008 with the EP "New Generation” and rose to stardom with its megahit single "Man Man Ha Ni," and went on to drop several more hits, including "Bingle Bingle" and "Shut Up."

The six-piece act celebrated its 15th anniversary this year by staging two shows in Tokyo and Osaka, Japan, in July.

Another veteran boy group, Teen Top, made its comeback in July after nearly three years.

Teen Top returned as a quartet with its fifth single album “4Sho” after the group’s leader C.A.P left the group in May over controversies sparked during a live broadcast with fans.

Teen Top brought its explosive energy back from when it debuted in 2010.

Their debut saw the K-pop scene vitalized with fast-tempo dance singles such as "Rocking," "Miss Right" and "No Perfume For You."

In July, the group met with its fans face-to-face for the first time in four years by holding a two-day concert in Seoul.

In the same month, Infinite released its seventh EP “13egin.”

The album was the first in five years and also the first after establishing its own agency, Infinite Co.

Having an agency of its own allowed the group to be in charge of the album production, from the concept of the music, and choreography to outfits, hair and makeup.

A full group return would not have been possible without Nam Woo-hyun, who had been diagnosed with a rare cancer earlier this year. He underwent surgery for a gastrointestinal stromal tumor in April and is in recovery.

Despite the doctor’s recommendation to rest after surgery, Nam decided to push ahead with Infinite's comeback as planned.

Infinite was even able to hold a full unit two-day concert in Seoul in August.

Last but not least, the legendary TVXQ dropped its ninth studio album “20&2” on Dec. 26 to celebrate its 20th anniversary.

TVXQ debuted as a quintet in December 2003 with its debut single, “Hug,” and garnered the biggest fandom among the second-generation K-pop acts thanks to its numerous hits.

The group wrote many firsts in K-pop history, from becoming the first Korean group to top the Japanese major music chart Oricon’s Weekly to holding the first-ever K-pop standalone concert at Tokyo dome back in 2009.

In 2010, three members left the group to form a separate trio, JYJ.

Changmin and Yunho have continued the team as a duo.

The group is scheduled to hold a standalone concert on Dec. 30-31 at the Inspire Arena, a new K-pop concert venue in Yeongjeong-do, Incheon.

This article is part of a series examining the K-pop scene in 2023. -- Ed.