In a studio that became the home ground for jazz singer Yun hee-jung for 30 years, concert posters, newspaper clippings, microphones, a keyboard and other musical instruments show the history of the 70-year-old vocalist.

Clad in leather pants and an eye-catching knitted hat, Yun brewed her coffee — the latest obsession for Yun, who lacks no energy. After expounding on her newfound passion for a while, she returns to her biggest passion: jazz.

Jazz came to her a bit later in life -- when she was 36 years old and the mother of two children. She was into gospels and someone told her to sing jazz, which led to the introduction of Lee Pan-Geun, a prominent figure in the jazz scene in South Korea. After meeting Lee, Yun became one of the pioneers who helped jazz become more familiar to the public.

For 15 years, from 1997 to 2011, she hosted a concert series titled "Yun Hee-jung & Friends." During this period, She would invite guest celebrities, ranging from movie stars to politicians, and train them how to sing a jazz song for three months. The period of 15 years has translated into 100 performances and 250 guests. Some of the participants include Lee Ha-nee, Song Il-kook, Park Kyung-lim, Park Sang-won and Ok Joo-hyun just to name a few.

“Trying to memorize the lyrics in English, I struggled. But I don't have regrets. The only regret I have is I didn't encounter jazz at an earlier time," Yun told The Korea Herald during an interview in her studio at Seocho-dong in Gangnam-gu on Nov. 21.

The "Yun Hee-jung & Friends" series came to an end in 2011, but she returned with another series, titled "Jazz Friends Party," this time, making it an annual event in May. She sings about three songs and her “friends” perform the rest.

"There are only two things about music: It's either easy to listen to or enjoyable to listen to. I am a singer who tries to make music that is easy to listen to. It's my kind of jazz," she said.

That’s why she would remake one trot song into a jazz style every time she does a concert.

To jazzify "ppongjjak" songs, also known as trot, she transforms them into jazz compositions. She plans to release an album early next year featuring these reimagined tracks. The album contains 10 of the most popular trot and pop songs that includes "Hymn of Wish," "Whiskey on the Rock," "Once Again" and more.

South Korea is inundated with audition programs, a phenomenon that was rare during her 20s. Nevertheless, Yun became an audition star of the first generation. In 1971, she made her debut through the TV program "National Singing Contest." The win effectively persuaded her family who initially opposed her prospects as a singer.

The month of December is special for Yun. It’s the month for her special concert series that she has carried out since 2000. The venue has changed from Walker Hill Hotel to The Westin Josun Seoul, from Novotel Ambassador Seoul Gangnam to Hall of Ansan Culture and Arts to the current Raum Social Venue.

Her daughter, Kim Soo-yeon, also accompanies Yun each concert. Known by her stage name Somerz, Kim initially made her debut in 2003 as a member of vocal group “Bubble Sisters.”

Actor Lee Pil-mo will take the stage as a special guest, along with another guest who will be only unveiled at the concert on Dec. 22.

The reason she takes the stage with "friends" and "guests"? She said it's because of her desire to share "jeong" and to establish a closer connection with the audience.

"Jeong" symbolizes a profound sense of warm-heartedness and affection that transcends mere attachments. When Koreans assess their relationships, they gauge the depth and quantity of "jeong" as a measure of their connection with others.

“Jazz is not passion, it’s compassion. I want to share 'jeong' through jazz and I want to be close to the public," Yun added.