Jung Ki-Yeol (born December 5, 1981), known professionally as Kai, is a South Korean singer and musical theatre actor.
 He is best known in musical theatre, and has starred in Korean productions of "A Tale of Two Cities", "The Three Musketeers" and "Phantom".
Sunmin (Hangul: 선민, "Katakana": ソンミン, born August 4, 1987) is a South Korean singer who speaks and sings in Korean, Japanese, and English.
 She debuted in 2006, with the single "Keep Holding You," a collaboration with the Japanese R&B singer Toshinobu Kubota.
 Her career was initially focused on the Japanese market, but her work became focused in South Korea from 2009 to 2010.
 She also contributed to original soundtracks of South Korean television series "Master of Study" and "Gloria (2010 TV series)".
 In 2010 to 2011, she was in the main South Korean musical production of "Jekyll & Hyde" as Lucy.
 In 2012 to 2013, she reprised her role as Lucy in the South Korean national tour.
 In spring 2013, Sunmin played Josephine in the South Korean production of "Arsène Lupin", the musical.
Michael Kiske (born January 24, 1968) is a German singer best known as the lead vocalist for the German power metal band Helloween.
 After his departure from the band, Kiske recorded four solo albums, participated on various metal and rock related projects, such as Avantasia, Place Vendome and Kiske/Somerville, while he also performed with numerous bands as a guest vocalist.
 In late 2009, he formed the hard rock / heavy metal band Unisonic and began touring again after 17 years of absence.
 On November 14, 2016 it was officially announced that Kiske will tour again with Helloween and Kai Hansen in 2017 and 2018.
Kai Michael Hansen (born 17 January 1963) is a heavy metal guitarist and vocalist.
Ji Hye-ran (born January 3, 1996), better known by her stage name Z.Hera, is a South Korean singer and actress.
 Z.Hera appeared on the documentary program "Human Theater" in 2006 as Shaolin Girl when she was 11 years old.
 She received attention after being the first South Korean singer to appear on the American social site BuzzFeed.
 She is known for her roles in "Moorim School" (2016) and "" (2016).
Helloween is a German power metal band founded in 1984 in Hamburg, Northern Germany by members of bands Iron Fist and Gentry.
 Its first line-up consisted of singer and guitarist Kai Hansen, bass guitarist Markus Grosskopf, guitarist Michael Weikath, and drummer Ingo Schwichtenberg.
 After the release of a self-titled EP and their debut album "Walls of Jericho" in 1985, it expanded into a quintet with the addition of singer Michael Kiske, Hansen choosing to focus on guitar instead.
 Under this line-up, they released the "Keeper of the Seven Keys" albums (1987 and 1988), which established Helloween as a notable heavy metal band and led to the creation of the power metal subgenre.
 However, Hansen left the band quickly after the release of "Part II" and was replaced by Roland Grapow.
 He then created the band Gamma Ray.
Woo Ji-seok (Korean: 우지석 ; born May 11, 1990), commonly known as Taewoon or ₩uNo is a South Korean singer, rapper, songwriter, and record producer.
 He is a former member of the South Korean boy band Speed and former member of the South Korean Coed group Coed School.
Gamma Ray is a power metal band from Hamburg, northern Germany, founded and fronted by Kai Hansen after his departure from the German power metal band Helloween.
 Hansen is the current lead vocalist, guitarist as well as the chief songwriter of Gamma Ray.
 The band is known as one of the most prominent bands of the German heavy metal scene.
Unisonic is a German hard rock/power metal supergroup, founded in November 10, 2009 by former Helloween singer Michael Kiske alongside Dennis Ward and Kosta Zafiriou from Pink Cream 69 and Mandy Meyer, formerly in Asia and Gotthard.
 In 2011 the band was joined by Gamma Ray leader and Helloween co-founder, Kai Hansen.
Park Mi-yeon (born September 16, 1990), better known by the stage name Serri, is a South Korean singer, songwriter and actress.
 She is best known as a member and leader of the South Korean girl group Dal Shabet.

Question: In between Kai Hansen and Serri who is a South Korean singer, songwriter and actress?
Answer: Park Mi-yeon