• 
  Seok-Hwan An

  unknown episodes
• 
  Yoo-Jeong Kim

   Gil Oh-sol
• 
  Jae-rim Song

   Mr. Choi
• 
  Hyo-Seop Ahn

   Jang Seon-kyul
• 
  Kyun-Sang Yoon

   Jang Seon-kyul (2018)
• 
  Seon Yu

  Secretary Gwon
• 
  Won-hae Kim

  16 episodes, 2018-2019
• 
  Do Hee Min

  Min Joo Yeon [Oh Sol's Best Friend]

• 
  In-ha Cha

  14 episodes, 2018-2019
• 
  Hak Jin

  Lee Dong Hyun
• 
  Do-Hyun Lee

  Gil Oh Dol [Oh Sol's Brother]
• 
  Jung Jae-Sung

  Coach
• 
  Hye-eun Kim

  Cha Mae-hwa (2018)
• 
  Kim Ki Nam

  Secretary Kim (2018)
• 
  Byung-ho Son

  CEO Yang (2018)