Lee Joon Ha / Lee Kwang Soo (293 episodes, 2006-2010)
Shin Ji / Hwang Jung Eum / Jung Hae Ri (293 episodes, 2006-2010)
Lee Yoon Ho / Jung Joon Hyuk (293 episodes, 2006-2010)
Lee Soon Jae (293 episodes, 2006-2010)
Lee Min Yong (223 episodes, 2006-2012)
Lee Min Ho (167 episodes, 2006-2007)
Hwang Chan Sung / Kim Bum (167 episodes, 2006-2007)
Park Hae Mi (167 episodes, 2006-2007)
Kang Se Ho (126 episodes, 2009-2010)
Julien (126 episodes, 2009-2010)
Kim Ja-Ok (126 episodes, 2009-2010)
Lee Hyun Kyung (126 episodes, 2009-2010)
Jung Bo Suk (126 episodes, 2009-2010)
Yoon Yoo Sun (123 episodes, 2011-2012)
Lee Soon-jae (17 episodes, 2006-2009)
Lee Min-ho / Hiker (16 episodes, 2006-2009)
Lee Yoon-Ho (15 episodes, 2006)
Nah Moon-hee (15 episodes, 2006)
Lee Jun-ha (15 episodes, 2006)
Park Hae-mi (15 episodes, 2006)
Lee Min-yong (15 episodes, 2006)
Shin Ji (13 episodes, 2006)
Seo Min-jeong (13 episodes, 2006)
Kim Bum (11 episodes, 2006)
Vice Principal / Principal (10 episodes, 2006-2009)
Jong-suk Ahn / Ahn jong-suk (10 episodes, 2011)
Ji-won Kim / Kim Ji-Won (10 episodes, 2011)
Kye-sang Yoon / Yoon Kye-Sang (10 episodes, 2011)
Su-jeong Ahn / Ahn Soo-Jung (10 episodes, 2011)
Nae-sang Ahn / Ahn Nae-Sang (10 episodes, 2011)
Jin-hee Baek (10 episodes, 2011)
Ji-seok Yoon (10 episodes, 2011)
Julien (10 episodes, 2011)
Ha-sun Park (10 episodes, 2011)
Kang Yoo-mi (9 episodes, 2006)
Hwang Chan-Sung (5 episodes, 2006)
Yum Seung-hyun (4 episodes, 2006)
Suna (3 episodes, 2006)
Detective Lee (2 episodes, 2006)
Shin Se-Kyung (2 episodes, 2009)
Jung Joon-Hyuk (2 episodes, 2009)
Lee Ji-Hoon (2 episodes, 2009)
Jung Hae-Ri (2 episodes, 2009)
Lee Hyun-Kyung (2 episodes, 2009)
Jung Bo-Suk (2 episodes, 2009)
Shin Shin-Ae (2 episodes, 2009)
Kim Ja-Ok (2 episodes, 2009)
Yoo Hee-Jin (1 episode, 2006)
Shin Dal-Ho (1 episode, 2009)
Kang Se Ho (1 episode, 2009)
Ji-Hoon's Blind Date (1 episode, 2009)
Park Kyung-rim (1 episode, 2009)
Soon-Jae's Secretary (1 episode, 2009)
Ji-hoon's junior (1 episode, 2009)
Hiker (1 episode, 2009)
Park Ha-Sun (1 episode, 2011)
Lee-Juck (1 episode, 2011)
Ahn Jong-Suk (1 episode, 2011)
Park Ji-Sun (1 episode, 2011)
Cassy (uncredited) (1 episode, 2012)