Question: Not Alone, is Zhang Liyin's fourth overall single, released on August 20, 2014 in China and August 22 in South Korea,Zhang held a showcase to support the release of the single, which was held at the Century Theater in Beijing, guests at the said event include Kim Jong-dae, a South Korean singer-songwriter and actor, better known by which stage name?

Context paragraphs:
Moving On (Zhang Liyin song): "Moving On" is Zhang Liyin's first Chinese single (second overall), released on October 29, 2009.  The title song is a remake of Ana Bárbara's "Deja", originally recorded in 2003; while "Love Me" is a remake of a song called "Baila".  "Moving On" was released in South Korea on October 30, 2009 in both physical and digital formats.

I Will (Zhang Liyin album): "星愿 (I Will)" is the official title of the debut studio album by Chinese singer Zhang Liyin, better known among English-speakers as simply "I WILL".  The album was released in various regions of China on March 3, 2008, and released in South Korea on March 12, 2008, which included two bonus Korean tracks.  The Asian Special Edition (CD+DVD) of the album was released on March 28, 2008 in Taiwan.  Two music videos of the same storyline were released on February 27, 2008 to complement the album release.

Insooni: Kim In-soon (Korean: 김인순 ; born April 5, 1957), better known by her stage name, Insooni (Korean: 인순이 ), is a South Korean singer.  She made her debut in 1978 in a group "Hee Sisters (Korean: 희자매 )".  Since then, she has recorded a total of 19 albums, 14 of them, regular.  She is now South Korea's acclaimed R&B diva with a wide range of fans, even though 35 years have passed since her debut.  She is one of the few singers who performed at Carnegie Hall in New York City, and earned several top prizes at broadcasters' annual award ceremonies.  She is distinguished by her rich, throaty voice on stage.  She was born to a South Korean mother and an African American father, who served in the U.S. military in South Korea, and was brought up by her mother alone, with the assistance of Pearl S. Buck International's child sponsorship program.

Timeless (Zhang Liyin song): "Timeless" is Zhang Liyin's debut single, released on September 8, 2006 in South Korea.  The song is a remake of Kelly Clarkson and Justin Guarini's duet, originally recorded in 2003; it has also been remade by Tina Arena and Kane Alexander in 2006.  A Chinese version of the single was released in 2007 in Taiwan.

Chen (singer): Kim Jong-dae (born September 21, 1992), better known by his stage name Chen, is a South Korean singer-songwriter and actor.  He is a member of the South Korean-Chinese boy group EXO and its sub-unit EXO-CBX, as well as S.M Entertainment's ballad group SM the Ballad.

Agape (song): Agape is Zhang Liyin's third overall single, released on August 2, 2014 in China and August 6 in Korea.  The song is dedicated to the victims of the 2008 Sichuan earthquake.  Co-written by Zhang Liyin and Taiwanese lyricist , the song is about a mother who allows her child to live at the expense of her own life.  The single's B-side track "Back Then" is a cover of the title song from Taiwanese film "You Are the Apple of My Eye".

Cha Hong: Kim Hyo-suk (Hangul: 김효숙; born 11 September 1981), better known by her stage name Cha Hong (Hangul: 차홍), is a South Korean celebrity hairdresser, and is the owner and founder of the Chahong Ardor beauty salon chain in South Korea.  Cha established her first hair salon back in August 2011, and currently owns a total of 3 salons and an academy.  Cha made her debut television appearance via SBS's Star King in February 2011, and now features frequently as guests on various South Korean television shows, such as Channel M's Get It Beauty and MBC's My Little Television.  Cha is renowned for the self-hair styling tips that she shares during her television appearances, and has since widened her media exposure through channels such as radio shows, blogs, social media websites and home shopping networks.

Juniel: Choi Seo-ah (Korean: 최서아; born Choi Jun-hee on September 3, 1993) better known by her stage name Juniel (Hangul: 주니엘, often stylized as JUNIEL) is a South Korean singer-songwriter.  She began her career in Japan before eventually debuting in South Korea.  She was first known as 'Junie', but eventually changed her stage name to 'Juniel', which was derived from combining her name, Junie, and L for 'love'.  She was also a member of the duo Romantic J with CNBLUE's Lee Jong-hyun under former label FNC Entertainment.  In 2016, Juniel announced on her social media that she legally changed her native name from 최준희 (Choi Jun-hee) to 최서아 (Choi Seo-ah).

Zhang Liyin: Zhang Liyin (born February 28, 1989), better known in South Korea as Jang Ri-in, is a Chinese singer.  She is a former member of S.M. Entertainment's project group S.M.  The Ballad.  Subject to much publicity, Zhang was nicknamed the "Chinese BoA" and the next leader of the Korean Wave.  She speaks both Mandarin, which is her first language, and fluent Korean, and has released singles in both China and South Korea, singing in both languages.

Not Alone (Zhang Liyin song): Not Alone (我一个人) is Zhang Liyin's fourth overall single, released on August 20, 2014 in China and August 22 in South Korea.  The song is a remake of 'By Myself' (나 혼자서) from the SBS drama "Ja Myung Go" which "Girl's Generation" member Tiffany sang back in 2009.  Zhang Liyin had mentioned that the song is a follow up track and a continuation of the storyline of "Agape" during her YouTube Interview with Victoria and Tao.  In a press release from SM Entertainment on September 18, they announced that the song will be Zhang Liyin's fourth single.  It was released on September 20, 2014 in China through Baidu and then later released in South Korea through Korean music sites MelOn, Genie, Naver and Bugs on September 22.  Zhang held a showcase to support the release of the single, which was held at the Century Theater in Beijing.  EXO members Tao and Chen were guests at the said event.

Supporting paragraphs: Not Alone (Zhang Liyin song) Chen (singer)
Answer: Chen